# GCN_circulars

GRB_name: GRB170803A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21411
SUBJECT: GRB 170803A: Swift/UVOT Detection
DATE:    17/08/04 13:04:24 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and S. J. LaPorte (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170803A
88 s after the BAT trigger (LaPorte et al., GCN Circ. 21405).
GRB 170803A was also triggered by Fermi GBM
(Veres and Meegan GCN Circ. 21406)
A fading source consistent with the XRT position
(Beardmore et al., GCN Circ. 21407)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  11:39:44.11 = 174.93380 (deg.)
    Dec (J2000) = -16:18:38.0  = -16.31055 (deg.)
with an estimated uncertainty of 0.44 arc sec. (radius, 90% confidence).

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white_FC            88          238          147         18.10 +/- 0.06
white              580         2241          322         19.69 +/- 0.12
u_FC               300          550          246         18.58 +/- 0.16
u                  775         2366          175         >19.34
b                  556         2386          191         20.02 +/- 0.35
uvw1              6216        23821          982         >20.74
uvm2             17025        17715          679         >20.57
uvw2              5602        30135          990         >21.05

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170803A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21412
SUBJECT: GRB 170803A: Swift-BAT refined analysis
DATE:    17/08/04 14:01:17 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF/USRA), S. J. LaPorte (PSU),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+200 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170803A (trigger #766081)
(LaPorte et al., GCN Circ. 21405).  The BAT ground-calculated position is
RA, Dec = 174.947, -16.312 deg which is
  RA(J2000)  =  11h 39m 47.2s
  Dec(J2000) = -16d 18' 41.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 94%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~T-0.7 s and ends at ~T+4 s. The main peak occurs at ~T+0.1 s
T90 (15-350 keV) is 3.82 +- 0.23 sec (estimated error including systematics).

The time-averaged spectrum from T-0.69 to T+4.14 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.65 +- 0.28,
and Epeak of 100.2 +- 20.5 keV (chi squared 47.53 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 9.8 +- 0.4 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T-0.12 sec in the 15-150 keV band is
6.5 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.39 +- 0.06 (chi squared 71.10 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/766081/BA/


GRB_name: GRB170804A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21413
SUBJECT: GRB 170804A: Enhanced Swift-XRT position
DATE:    17/08/04 16:14:01 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1208 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 170804A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 6.39233, -64.78429 which is equivalent
to:

RA (J2000): 00h 25m 34.16s
Dec (J2000): -64d 47' 03.4"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170804A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21414
SUBJECT: GRB 170804A: Swift-XRT refined Analysis
DATE:    17/08/04 20:01:28 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), K.L. Page (U. Leicester), B. Mingo (U. Leicester),
A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia
(ASDC), A. D'Ai (INAF-IASFPA), S. J. LaPorte (PSU) and A. Cholden-Brown
report on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 170804A (Cholden-Brown et
al. GCN Circ. 21410), from 112 s to 19.6 ks after the  BAT trigger. The
data comprise 95 s in Windowed Timing (WT) mode (the first 8 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by Evans
et al. (GCN Circ. 21413).

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.90 (+0.34, -0.22), followed by a break at T+519 s to
an alpha of 1.13 (+0.20, -0.13).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.37 (+0.16, -0.13). The
best-fitting absorption column is  consistent with the Galactic value
of 1.8 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has
a photon index of 1.97 (+0.16, -0.14) and a best-fitting absorption
column consistent with the Galactic value. The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.2 x 10^-11 (3.4 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.8 (+2.4, -0.0) x 10^20 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.97 (+0.16, -0.14)

If the light curve continues to decay with a power-law decay index of
1.13, the count rate at T+24 hours will be 8.3 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x
10^-14 (2.8 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00766194.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170804A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21415
SUBJECT: GRB 170804A: Swift/UVOT Detection 
DATE:    17/08/04 21:03:59 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (U. Warwick) and A. Cholden-Brown (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170804A
132 s after the BAT trigger (Cholden-Brown et al., GCN Circ. 21410).

A fading source consistent with the XRT position
(Evans et al., GCN Circ. 21413) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
     RA  (J2000) =   0:25:34.29 =   6.39288 (deg.)
     Dec (J2000) = -64:47:03.1  = -64.78419 (deg.)

with an estimated uncertainty of 0.5 arc sec. (radius, 90% confidence).

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
white_FC         132          281           147         18.9 +/- 0.1
white            871          1020          147         20.0 +/- 0.2
u_FC             289          539           246         18.7 +/- 0.1
v         796          1243           58         >18.7
b                545          565            19         18.9 +/- 0.4
uvw1             671          1292           78         >19.0
uvw2             596          1392           97         >19.2


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).








---------------------------------------------

Dr Samantha Oates

Leverhulme Early Career Fellow
Department of Physics
University of Warwick
Coventry
CV4, UK
Tel:  +44 (024) 765 23383
Email: s.oates@warwick.ac.uk<mailto:s.oates@warwick.ac.uk>
-----------------------------------------------


GRB_name: GRB170804A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21416
SUBJECT: GRB 170804A: Swift-BAT refined analysis
DATE:    17/08/05 15:45:14 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC),
A. Cholden-Brown (PSU), J. R. Cummings (CPI),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170804A (trigger #766194)
(Cholden-Brown et al., GCN Circ. 21410).  The BAT ground-calculated position is
RA, Dec = 6.404, -64.781 deg which is
  RA(J2000)  =  00h 25m 37.0s
  Dec(J2000) = -64d 46' 50.9"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 75%.

The mask-weighted light curve shows several over-lapping pulses that
start at ~T0 and end at ~T+60 s. T90 (15-350 keV) is 43.4 +- 9.8 sec
(estimated error including systematics).

The time-averaged spectrum from T+1.98 to T+60.90 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.67 +- 0.13.  The fluence in the 15-150 keV band is 1.3 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+25.10 sec in the 15-150 keV band
is 0.9 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/766194/BA/


GRB_name: GRB170804A
Detection_method: LCO
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21417
SUBJECT: GRB 170804A: LCO Observations
DATE:    17/08/05 16:53:45 GMT
FROM:    Antonino Cucchiara at UVI  <antonino.cucchiara@uvi.edu>

A. Cucchiara, D. Morris (U. of the Virgin Islands), and
N. Orange (OrangeWave), report on behalf of a larger
collaboration:

"On August 4.79 UT  (T_0 +7.0h) we began observing the
center of the field of GRB 170804A (Cholden-Brown et al.
GCN 21410, Emery et al. GCN 21411) using the Las Cumbres
Observatory 1m telescope located in Siding Spring
Observatory.

Under poor sky conditions (seeing ~2.6 arcseconds) we
performed a series of 5x240s observations in SDSS r' and iâ€™
bands for a total of 20 minutes on sky in each filter at
average airmass of 1.3.

In the full median stacked images we identified no optical
counterpart within the center of the Swift-XRT refined position
or at the UVOT optical counterpart location (Evans et al.
GCN 21413, Emery et al. GCN 21411) at the following
3-sigma limits:

r' > 21.4 mag
i' > 21.1 mag

These magnitudes are calibrated against nearby USNO-B1 sources,
converted in SDSS bands, and not corrected for Galactic extinction."


GRB_name: GRB170803A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21418
SUBJECT: GRB 170803A: Swift/BAT spectral lag results
DATE:    17/08/05 20:05:59 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. P. Norris (BSU), S. D. Barthelmy (GSFC),
S. B. Cenko (GSFC),  A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift-BAT team:

We report the spectral lag analysis for GRB 170803A
(LaPorte et al., GCN Circ. 21405) based on the BAT data.
The lag analysis finds a lag of 43 (+12, -12) ms for the
100-350 keV to 25-50 keV band, and 76 (+40, -26) ms for
the 50-100 keV to 15-25 keV band. These values are
consistent with those of long GRBs.


GRB_name: GRB170728B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21419
SUBJECT: GRB 170728B: TShAO, SAO RAS and AbAO optical observations
DATE:    17/08/07 10:23:04 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volnova (IKI),  A. Kusakin (Fesenkov Astrophysical Institute), A.S. 
Moskvitin (SAO RAS), O.I. Spiridonova (SAO RAS),  R. Inasaridze (AbAO), I. 
Reva (Fesenkov Astrophysical Institute),  E. Mazaeva (IKI), A. Pozanenko 
(IKI)   report on behalf of larger GRB follow-up collaboration:

We observed the field of the Swift GRB 170728B (Cenko et al., GCN 21371) 
with Zeiss-1000 of SAO RAS (July 29, August 4,5 ), AS-32 telescope of AbAO 
(July 29) and  Zeiss-1000  telescope of Tien Shan Astronomical Observatory 
(July  30,31 August 1,6).  Below we report the photometry of the optical 
afterglow (D'Avanzo et al., GCNs 21372, 21373; Heintz  et al., GCN 21374; 
Guidorzi   et al., GCN 21375) and upper limits of our observations. 
Preliminary photometry is following:

Date       UT start   t-T0    Filter Exp. OT     Err. UL  Telescope
                       (mid, days)     (s)             (3 sigma)

2017-07-29 00:41:51  0.07228  R    600   n/d     n/d  18.6  Z-1000 SAO
2017-07-29 17:27:49  0.79594 CR   43*60  n/d     n/d  20.4  AS-32  AbAO
2017-07-30 16:12:56  1.79815  R  97*120   21.93  0.25  22.1  Z-1000 TSHAO
2017-08-01 15:12:51  3.72304  R  60*120  n/d     n/d  21.6  Z-1000 TSHAO
2017-08-04 00:41:51  5.98081  R  41*300   22.6  0.23  22.8  Z-1000 SAO

The photometry is based on nearby USNO-B1.0 stars

1601-0108291 15:52:31.54 +70:09:31.7 R2 17.95

1601-0108289 15:52:28.99 +70:09:26.3 R2 18.08

1601-0108260 15:51:57.87 +70:09:53.8 R2 16.87

1601-0108254 15:51:50.88 +70:08:41.2 R2 15.04

1601-0108262 15:52:03.24 +70:07:32.0 R2 16.01

Coordinates of the afterglow obtained from observation on July 30 are 
(J2000)
15 51 55.5179 +70 07 21.123  with uncertainties on both coordinates of  0.2 
arces which is compatible with coordinates of TNG (D'Avanzo et al., GCN 
21373) and VLA (Fong  et al., GCN 21395). The  finding chart can be found in
http://grb.rssi.ru/GRB170728B/GRB170728B_TShAO_R_170730.png

The light curve of the afterglow based on  observations above and photometry 
reported in GCNs (Dintinjana et al., GCN 21394; Watson GCN 21389;   D'Avanzo 
et al., GCN 21372; Heintz  et al., GCN 21374; Guidorzi   et al., GCN 21375) 
can be found in
http://grb.rssi.ru/GRB170728B/GRB170728B_lc+GCNs_v2.png
Based on our observation on July, 30 (~ 1.8 days after burst onset) one can 
suggest that the OT experienced  rebrightening at that epoch. 


GRB_name: GRB170807A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21420
SUBJECT: GRB 170807A: Swift detection of a burst
DATE:    17/08/07 22:08:20 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J.D. Gropp (PSU), S. D. Barthelmy (GSFC), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU) and A. Tohuvavohu (PSU) report on behalf
of the Swift Team:

At 21:56:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170807A (trigger=766821).  Swift could not slew to the 
burst due to a Sun constraint.  The BAT on-board calculated location is 
RA, Dec 143.379, -17.329 which is 
   RA(J2000) = 09h 33m 31s
   Dec(J2000) = -17d 19' 44"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed two FRED
structures with a total duration of about 40 sec.  The peak count rate
was ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 06:56 UT on 2017 October 03. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170805A
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21421
SUBJECT: GRB 170805A: Insight-HXMT detection
DATE:    17/08/08 01:27:32 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

X. Ma, C. K. Li, S. L. Xiong, C. Z. Liu, X. F. Li,
Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-08-05T14:38:34.40 (T0),
Insight-HXMT detected GRB 170805A (trigger ID: HEB170805610)
in a routine search of the data, which was also observed by
Swift/BAT (trigger #766372).

The Insight-HXMT light curve mainly consists of a single pulse
with a duration (T90) of 0.496 s measured from T0+0.014 s.
The 50-ms peak rate, measured from T0+0.35 s, is 3083.8 cnts/sec.
The total counts from this burst is 1092.4 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170805610_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170808A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21422
SUBJECT: GRB 170808A: MAXI/GSC detection
DATE:    17/08/08 04:38:24 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko@crab.riken.jp>

H. Kawai (Chuo U.), S. Nakahira, M. Serino, T. Mihara, M. Sugizaki,
W. Iwakiri, M. Shidatsu, M. Matsuoka (RIKEN), 
H. Negoro, M. Nakajima, T. Kawase, A. Sakamaki (Nihon U.),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA),
N. Kawai, S. Sugita, T. Yoshii, Y. Tachibana, S. Harita, Y. Muraki, K. Morita (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka, T. Hashimoto (AGU), 
H. Tsunemi, T. Yoneyama (Osaka U.), 
Y. Ueda, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), 
Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), 
M. Yamauchi, C. Hanyu, K, Hidaka (Miyazaki U.), 
T. Kawamuro (NAOJ), 
K. Yamaoka (Nagoya U.) 
report on behalf of the MAXI team:

 The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at UT 02:47:57 UT on 2017 August 8. 
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (157.564 deg, -28.277 deg) = (10 30 15, -28 16 37) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.34 deg and 0.33 deg, respectively. 
The roll angle of long axis from the north direction is 64.0 deg counterclockwise. 
We estimated a rectangular error box for the transient source with the following corners:
(157.227, -28.921) deg = (10 28 54, -28 55 16) (J2000) 
(157.014, -28.758) deg = (10 28 03, -28 45 29) (J2000) 
(158.133, -27.077) deg = (10 32 32, -27 04 37) (J2000) 
(158.343, -27.238) deg = (10 33 22, -27 14 16) (J2000).
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).

The X-ray flux averaged over the scan was 77 +- 18 mCrab
(2.0-4.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 01:15
and in the next transit at UT 04:20 with an upper limit of 20 mCrab for each.


GRB_name: GRB170807A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21423
SUBJECT: GRB 170807A: Swift-BAT refined analysis
DATE:    17/08/08 12:40:58 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), J. D. Gropp (PSU),
H. A. Krimm (NSF/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170807A (trigger #766821)
(Gropp et al., GCN Circ. 21420).  The BAT ground-calculated position is
RA, Dec = 143.434, -17.348 deg which is
  RA(J2000)  =  09h 33m 44.2s
  Dec(J2000) = -17d 20' 51.9"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.

The mask-weighted light curve shows a multi-peaked structure that starts at
~T0 and ends at ~T+50 s. The two main peaks occur at ~T+1 s and ~T+30 s,
respectively. T90 (15-350 keV) is 48.5 +- 11.7 sec (estimated error including systematics).

The time-averaged spectrum from T-0.42 to T+53.08 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.82 +- 0.15.  The fluence in the 15-150 keV band is 8.6 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.73 sec in the 15-150 keV band
is 1.4 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/766821/BA/


GRB_name: GRB170714A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21424
SUBJECT: GRB 170714A: ATCA detection of the radio counterpart
DATE:    17/08/08 13:13:31 GMT
FROM:    Luigi Piro at INAF  <luigi.piro@iaps.inaf.it>

L. Piro(INAF/IAPS), R. Ricci (INAF/IRA-Bologna), M. Wieringa (ATNF,CSIRO),
E. Troja(NASA/GSFC), K. Bannister (ATNF,CSIRO) and B. Gendre (UVI, USA) 
report:

We carried out a second observation of our monitoring campaign of the 
field of the ultralong GRB 170714A (D'Ai' et al. GCN 21340; Evans et al. 
GCN 21341; Kann et al. GCN 21345; Palmer et al. GCN 21347) with ATCA on 
2017 Aug 4 for 9 hours at 17 and 21 GHz.

We detect a source at:

RA: 02h17m23.96s
Dec: +01:59'32.9"

with a 90% error of ~2.5" in DEC and ~0.1" in RA, consistent with the 
position of the GRB X-ray counterpart by Chandra (Troja et al. GCN 21396) 
and the optical source reported by de Ugarte Postigo et al. (GCN 21346).

We associate this source to the radio afterglow of the burst. The flux 
measured at 19 GHz is 71 +/- 19 uJy.

In comparison to the first ATCA observation (Ricci et al. GCN 21360), the 
present configuration improves significantly the resolution and allows us 
to distinguish the radio afterglow from the unrelated source associated to 
the NOEMA observation (de Ugarte Postigo et al., GCN 21356).

We thank the ATCA staff for scheduling this target of opportunity observation.


GRB_name: GRB170724A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21425
SUBJECT: Konus-Wind observation of GRB 170724A
DATE:    17/08/08 13:17:35 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A.Kozlova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko,
and T. Cline on behalf of the Konus-Wind team, report:

The long GRB 170724A (Swift-BAT trigger #764204: Ukwatta et al.,
GCN 21364; Sakamoto et al., GCN 21365)
was detected by Konus-Wind (KW) in the waiting mode.

The burst light curve shows two emission episodes. The first
started at at ~T0(BAT)-508.6 s with a duration of ~247 s and the
second weaker episode, which corresponds to the BAT trigger,
started at ~T0(BAT)-20 s with a duration of ~91 s.

As observed by Konus-Wind, the first episode had a fluence of
5.49(-0.24,+0.26)x10^-5 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(BAT)-408.5 s, of 1.33(-0.16,+0.16)x10^-6 erg/cm2/s.
The second episode had a fluence of ~ 0.4 x10^-5 erg/cm2
(all in the 20 - 1000 keV energy range).

Modeling the KW 3-channel time-integrated spectrum of the first episode
(from ~T0(BAT)-508.6 s to ~T0(BAT)-261.3 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.36 (-0.78,+0.82), and Ep = 340 (-49,+77) keV.

Modeling the KW 3-channel time-integrated spectrum of the second episode
(from ~T0(BAT)-20 s to ~T0(BAT)+71.4 s)
by a simple power-law model yields a power law
index of -2.06(-0.13,+0.24), chi2=0.9/1 dof.

The KW light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB170724A/

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.


GRB_name: GRB170801A
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21426
SUBJECT: GRB 170801A: Insight-HXMT detection
DATE:    17/08/08 16:01:29 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

J. Y. Liao, C. K. Li, S. L. Xiong, C. Z. Liu, X. F. Li,
Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-08-01T04:59:55.250 (T0),
Insight-HXMT detected GRB 170801A (trigger ID: HEB170801208)
in a routine search of the data, which was also observed by
CALET (trig time: 2017-08-01T04:59:55.16).

The Insight-HXMT light curve consists of single pulse
with a duration (T90) of 0.029 s measured from T0+0.009 s.
The 10-ms peak rate, measured from T0+0.020 s, is 12839.2 cnts/sec.
The total counts from this burst is 381 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170801208_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170805A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21427
SUBJECT: IPN Triangulation of GRB 170805A (short)
DATE:    17/08/08 17:20:27 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

A short-duration GRB 170805A (Ma et al., GCN Circ. 21421)
was detected by Swift (BAT), Insight-HXMT, INTEGRAL (SPI-ACS), and
Mars-Odyssey (HEND) at about 52714 s UT (14:38:34).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   269.235 (17h 56m 56s) -18.322 (-18d 19' 19")
  Corners:
   269.038 (17h 56m 09s) -20.543 (-20d 32' 36")
   268.879 (17h 55m 31s) -20.576 (-20d 34' 34")
   269.536 (17h 58m 09s) -16.073 (-16d 04' 22")
   269.697 (17h 58m 47s) -16.036 (-16d 02' 11")
  ---------------------------------------------
The error box area is 2378 sq. arcmin, and its maximum
dimension is 4.6 deg (the minimum one is 8.8 arcmin).
The Sun distance was 135 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170805_T52714/IPN


GRB_name: GRB170805B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21428
SUBJECT: IPN Triangulation of GRB 170805B (short/hard)
DATE:    17/08/08 17:27:03 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team, and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
report:

A short-duration GRB 170805B was detected by Konus-Wind,
INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND)
at about 51525 s UT (14:18:45).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   137.274 (09h 09m 06s) +69.613 (+69d 36' 46")
  Corners:
   135.477 (09h 01m 54s) +69.580 (+69d 34' 49")
   136.562 (09h 06m 15s) +69.715 (+69d 42' 55")
   139.059 (09h 16m 14s) +69.622 (+69d 37' 18")
   137.975 (09h 11m 54s) +69.506 (+69d 30' 23")
  ---------------------------------------------
The error box area is 506 sq. arcmin, and its maximum
dimension is 1.25 deg (the minimum one is 9.6 arcmin).
The Sun distance was 52 deg.

This box may be improved.

Note that the positions of GRB 170805A and 170805B are inconsistent
with one another, ruling out a repeating source origin such as
a single magnetar.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170805_T51527/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170808B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21429
SUBJECT: GRB 170808B: Fermi GBM observation
DATE:    17/08/09 04:42:21 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P Veres and C Meegan (both UAH)
report on behalf of the Fermi GBM Team:

"At 22:27:43.10 UT on 8 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170808B (trigger 523924068 / 170808936).

The on-ground calculated location, using the GBM trigger
data, is RA = 146.49, DEC = -2.96 (J2000 degrees,
equivalent to 09 h 46 m, -02 d 58 '), with an uncertainty
of 1 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

This burst was also independently detected by INTEGRAL SPI-ACS.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high fluence
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground best location is 69 degrees.

The GBM light curve shows multiple overlapping pulses
with a duration (T90) of about 17.7 s (50-300 keV).
The time-averaged spectrum from T0 to T0+27.1 s is
best fit by a Band function with Epeak = 262 +/- 5 keV,
alpha = -1.01+/- 0.01, and beta = -2.30 +/- 0.03.

The event fluence (10-1000 keV) in this time interval is
(1.176 +/- 0.005)E-4 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+15.9 s in the 10-1000 keV band
is 169.4 +/- 0.7 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170808B
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21430
SUBJECT: GRB 170808B: Fermi LAT Detection
DATE:    17/08/09 05:59:27 GMT
FROM:    Daniel Kocevski at GSFC  <daniel.kocevski@nasa.gov>

F. Longo (University and INFN, Trieste) and D. Kocevski (NASA MSFC) report on behalf of the Fermi-LAT team:

At 22:27:43.10 UT on August 08, 2017, Fermi-LAT detected high-energy emission from GRB 170808B, which was also detected by Fermi-GBM (Veres and Meegan GCN 21429). 
The best LAT on-ground location is found to be
RA, Dec  145.66, 2.18 deg, J2000
with an error radius of 0.34 deg (90% containment, statistical error only). This was 69 deg from the LAT boresight at the time of the trigger and triggered an autonomous repoint of the spacecraft.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the GBM detection with high significance.
The highest-energy photon is a 1.62 GeV event which is observed 162 seconds after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Francesco Longo (francesco.longo@ts.infn.it).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.

[GCN OPS NOTE(09aug17):  Per author's request, the extraneous url listed in the original distribution has been removed.]


GRB_name: GRB170728B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21441
SUBJECT: GMRT upper limit on the radio afterglow of GRB 170728B
DATE:    17/08/10 06:40:18 GMT
FROM:    Poonam Chandra at TIFR  <poonam@ncra.tifr.res.in>

Poonam Chandra & A. J. Nayana (NCRA-TIFR, India) report:

We observed the short hard burst GRB 170728B (Cenko et al., GCN Circ. 21371) with the Giant Metre Wave Radio Telescope (GMRT) at 1390 MHz band on 2017 August 09.61 UT, i.e. 11.65 days after the burst. We do not see any significant radio emission at the burst position (Dâ€™Avanzo et al. GCN Circ. 21373). The 3-sigma upper limit on the GRB radio flux density is 140 uJy.

We thank the GMRT staff for scheduling these observations. 


GRB_name: GRB170805B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21442
SUBJECT: Konus-Wind observation of GRB 170805B
DATE:    17/08/10 11:41:06 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A.Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration GRB 170805B
(IPN triangulation: Hurley et al., GCN 21428)
triggered Konus-Wind at T0=51527.165 s UT (14:18:47.165).

The burst light curve shows a single pulse
which starts at T0-32 ms and has a total duration of ~0.2 s.

As observed by Konus-Wind, the burst
had a fluence of 1.23(-0.21,+0.46)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.008 s,
of 2.25(-0.47,+0.89)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

Since the most intense part of the burst was detected before
the trigger, the spectral analysis was performed using
the KW 3-channel light curve data.

Modeling the KW 3-channel time-integrated spectrum
(from T0-0.032 s to T0+0.146 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -0.97 (-0.15,+0.19), and Ep = 720 (-192,+474) keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170805_T51527/

All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170803B
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21443
SUBJECT: GRB 170803B: Insight-HXMT detection
DATE:    17/08/10 12:10:33 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

X. Ma, S. L. Xiong, C. K. Li, J. Y. Liao, Y. Huang, X. B. Li,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao,
A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU),
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, H. Y. Wang, M. Wu,
Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-08-03T22:00:31.78 (T0),
Insight-HXMT detected GRB 170803B (trigger ID: HEB170803917)
in a routine search of the data, which was also observed by
Konus-Wind (trig time: 22:00:35.981 UT).

The Insight-HXMT light curve shows a multi-peaked structure
with a duration (T90) of 0.27 s measured from T0.
The 20-ms peak rate, measured from T0+0.2 s, is 12443.1 cnts/sec.
The total counts from this burst is 1741.8 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170803917_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170805B
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21444
SUBJECT: GRB 170805B: Insight-HXMT observation
DATE:    17/08/10 12:16:32 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

X. Ma, C. K. Li, Y. Huang, J. Y. Liao, S. L. Xiong, C. Z. Liu,
X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang,
Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU),
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, H. Y. Wang, M. Wu,
Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-08-05T14:18:49.70 (T0),
Insight-HXMT detected GRB 170805B (trigger ID: HEB170805596)
in a routine search of the data, which was also observed by
Konus-Wind (Kozlova et al., GCN 21442), INTEGRAL (SPI-ACS), and
Mars-Odyssey (HEND) (Hurley et al., GCN 21428).

The Insight-HXMT light curve mainly consists of a single pulse
with a duration (T90) of 0.035 s measured from T0+0.0005 s.
The 10-ms peak rate, measured from T0+0.02 s, is 6662.3 cnts/sec.
The total counts from this burst is 224 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170805596_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170808B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21447
SUBJECT: Konus-Wind observation of GRB 170808B
DATE:    17/08/10 18:38:28 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A.Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, very bright GRB 170808B
(Fermi GBM observation: Veres et al., GCN 21429;
Fermi LAT Detection: Longo et al., GCN 21430)
triggered Konus-Wind at T0=80859.187 s UT (22:27:39.187).

The burst light curve shows a double-peaked structure
which starts at ~T0-2.3 s and has a total duration of ~18.5 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst
had a fluence of 2.20(-0.08,+0.08)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+15.008 s,
of 7.54(-1.02,+1.03)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+23.808 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.92(-0.06,+0.07),
the high energy photon index beta = -2.33(-0.09,+0.07),
the peak energy Ep = 238(-16,+17) keV
(chi2 = 96/98 dof)

The spectrum near the maximum count rate
(measured from T0+14.848 to T0+15.616 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.52(-0.12,+0.13),
the high energy photon index beta = -2.45(-0.13,+0.10),
the peak energy Ep = 282(-26,+29) keV
(chi2 = 80/67 dof)

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170808_T80859/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170810A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21449
SUBJECT: GRB 170810A: MASTER-NET very bright OT detection 
DATE:    17/08/10 22:17:00 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, 
P.Balanutsa,
A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

V. Yurkov, A. Gabovich, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk


D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory

R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in IAC was pointed to the  GRB170810A 25 sec after notice time 
and 45 sec after trigger time at 2017-08-10 22:02:26 UT. On our first (10s 
exposure)  set we  found very bright OT.

Mag: 11.258
Ra: 187.938775
Dec: 3.660714

  The message may be cited.

The observations made on zenit distance = 85 degrees, galaxy latitude b = 
66 degree.
The moon (90 % bright part) is  4 degrees above the horizon. The distance 
between  moon and  object is 169
The sun  altitude  is -27.0 degree.
The object can be observed till sunrise at 2017-08-11 06:32:12.


GRB_name: GRB170810A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21450
SUBJECT: GRB 170810A: Swift detection of a burst with a bright optical counterpart
DATE:    17/08/10 22:39:41 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. L. Gibson (U Leicester), D. N. Burrows (PSU), J. A. Kennea (PSU),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the
Swift Team:

At 22:01:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170810A (trigger=767284).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 187.950, +3.647 which is 
   RA(J2000) = 12h 31m 48s
   Dec(J2000) = +03d 38' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of 160 sec. The peak count rate 
was ~2600 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 22:02:57.5 UT, 76.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
187.9389, 3.6603 which is equivalent to:
   RA(J2000)  = 12h 31m 45.33s
   Dec(J2000) = +03d 39' 37.0"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 62 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.23 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.2
(+1.98/-1.79) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 4.45e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 876 seconds after the BAT trigger. There is a candidate afterglow in
the list of sources generated on-board at
  RA(J2000)  = 12:31:45.31 = 187.93881
  DEC(J2000) = +03:39:38.9  = 3.66080
with a 90%-confidence error radius of about 1.10 arc sec. This position is 3.5
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.87. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.03. 

An earlier UVOT finding chart exposure, starting 85 seconds after the 
BAT trigger, showed that the counterpart was much brighter at that time. 
However, this brightness precluded automatic analysis.  
Results for this early bright detection will be presented later. 

The original GCN notice of this burst suggested an association with the
galaxy NGC4496A.  However, the apparent separation from this galaxy,
0.295 deg, implies that these two objects are not related. 

Burst Advocate for this burst is S. L. Gibson (slg44 AT le.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170810A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21451
SUBJECT: GRB 170810A: Enhanced Swift-XRT position
DATE:    17/08/11 01:10:17 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1301 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 170810A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 187.93852, +3.66084 which is equivalent
to:

RA (J2000): 12h 31m 45.24s
Dec (J2000): +03d 39' 39.0"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170810A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21452
SUBJECT: GRB 170810A: Fermi-LAT detection
DATE:    17/08/11 02:24:00 GMT
FROM:    Judith Racusin at GSFC  <judith.racusin@nasa.gov>

J. L. Racusin (NASA/GSFC), E. Burns (NASA/GSFC), D. Kocevski (NASA/MSFC), F. Longo (University 
and INFN, Trieste), J. McEnery (NASA/GSFC), S. Razzaque (Johannesburg), G. Vianello (Stanford), 
report on behalf of the Fermi-LAT team:

Fermi-LAT detected high-energy emission from GRB 170810A, which trigger Fermi-GBM (trigger 
524095306 / 170810918) and Swift-BAT (Gibson et al, GCN 21450) at 22:01:41 on August, 10, 2017.

The best LAT on-ground location is found to be

RA, Dec = 187.5, 3.33 (J2000)

with an error radius of 0.53 deg (90 % containment, statistical error only), which is consistent with the 
Swift BAT, XRT, and UVOT positions (Gibson et al, GCN 21450; Goad et al., GCN 21451), as well as 
MASTER-NET (Rebolo et al, GCN 21449).

This was 60 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally 
correlated with the trigger with high significance.

The highest-energy photon is a 2.3 GeV event which is observed 34 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin@nasa.gov).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater 
than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and 
many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB170810A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21453
SUBJECT: GRB 170810A: Fermi GBM observation
DATE:    17/08/11 03:08:08 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P Veres and C Meegan (both UAH)
report on behalf of the Fermi GBM Team:

"At 22:01:41.58 UT on 10 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170810A (trigger 524095306 / 170810918).
which was also detected by the Swift/BAT (Gibson et al., GCN 21450) and
Fermi LAT (Racusin at al., GCN 21452). The GBM on-ground location is
consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 60 degrees.

The GBM light curve shows  multiple pulses
with a duration (T90) of about 137 s (50-300 keV).
The time-averaged spectrum from T0-6.1 s to T0+67.6 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.79 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 267 +/- 34 keV.


The event fluence (10-1000 keV) in this time interval is
(1.0 +/- 0.6)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+38.4 s in the 10-1000 keV band
is 2.6 +/- 0.2 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170810A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21454
SUBJECT: GRB 170810A: Swift/UVOT Detection
DATE:    17/08/11 04:04:43 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 170810A: Swift/UVOT Detection

S. J. LaPorte (PSU) and S. L. Gibson (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170810A
85 s after the BAT trigger (Gibson et al., GCN Circ. 21450).
A source consistent with the XRT position
(Goad et al. GCN Circ. 21451)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  12:31:45.33 = 187.93889 (deg.)
    Dec (J2000) = +03:39:38.9  =   3.66081 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               85          235          147         14.64 +/- 0.02
v                  628          648           20         15.88 +/- 0.13
b                  554          574           20         16.62 +/- 0.10
u                  299         1493          281        >19.3
w1                 677         1473           97        >18.9
w2                 604          623           19        >18.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170810A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21455
SUBJECT: GRB 170810A: Swift-XRT refined Analysis
DATE:    17/08/11 06:05:07 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAB), A. Cholden-Brown (PSU), S. J. LaPorte (PSU), J.A. Kennea
(PSU) and S.L. Gibson report on behalf of the Swift-XRT team:

We have analysed 6.8 ks of XRT data for GRB 170810A (Gibson et al. GCN
Circ. 21450), from 66 s to 18.7 ks after the  BAT trigger. The data
comprise 387 s in Windowed Timing (WT) mode (the first 9 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Goad et al.
(GCN Circ. 21451).

The late-time light curve (from T0+4.6 ks) can be modelled with a
power-law decay with a decay index of alpha=1.33 (+/-0.13).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.60 (+/-0.04). The
best-fitting absorption column is  3.5 (+1.0, -0.9) x 10^20 cm^-2, in
excess of the Galactic value of 2.2 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.93 (+0.11, -0.10)
and a best-fitting absorption column of 5.5 (+2.4, -2.3) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.4 x 10^-11 (3.8 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.5 (+2.4, -2.3) x 10^20 cm^-2
Galactic foreground: 2.2 x 10^20 cm^-2
Excess significance: 2.4 sigma
Photon index:      1.93 (+0.11, -0.10)

If the light curve continues to decay with a power-law decay index of
1.33, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.0 x
10^-13 (4.6 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00767284.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170810A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21458
SUBJECT: GRB 170810A: Swift-BAT refined analysis
DATE:    17/08/11 15:26:06 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
S. L. Gibson (U Leicester), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
  
Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170810A (trigger #767284)
(Gibson, et al., GCN Circ. 21450).  The BAT ground-calculated position is
RA, Dec = 187.928, 3.664 deg which is
    RA(J2000)  =  12h 31m 42.8s
    Dec(J2000) = +03d 39' 49.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 93%.

The mask-weighted light curve shows a complex multi-peaked structure that
starts at ~T-20 s and ends at ~T+180 s.  The brightest peak occurs at ~T+0.5 s.
T90 (15-350 keV) is 152.4 +- 21.5 sec (estimated error including systematics).
  
The time-averaged spectrum from T-24.33 to T+157.74 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.24 +- 0.07.  The fluence in the 15-150 keV band is 4.8 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.15 sec in the 15-150 keV band
is 1.2 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.
  
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/767284/BA/


GRB_name: GRB170626A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21460
SUBJECT: GRB 170626A: 15 GHz upper limits from AMI
DATE:    17/08/11 17:48:40 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170626A (Marshall et al., GCN 21264) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2016 Jun 26.51, Jun 28.76, Jun 
29.67 and Jul 04.66 (UT) do not reveal any radio source at the XRT 
location (Cholden-Brown et al., GCN 21267), with 3sigma upper limits of 
120 uJy, 138 uJy, 84 uJy and 132 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170710B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21461
SUBJECT: GRB 170710B: 15 GHz upper limits from AMI
DATE:    17/08/11 17:50:43 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array triggered on the Swift alert for GRB 170710B (Palmer 
et al., GCN 21316) as part of the 4pisky program, and subsequent follow 
up observations were obtained up to 10 days post-burst. Our observations 
at 15 GHz on 2016 Jul 12.3, Jul 13.26, Jul 15.29 and Jul 19.23 (UT) do 
not reveal any radio source at the BAT location (Palmer et al., GCN 
21316), with 3sigma upper limits of 153 uJy, 93 uJy, 93 uJy and 222 uJy 
respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170710C
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21462
SUBJECT: GRB 170710C: 15 GHz upper limits from AMI
DATE:    17/08/11 17:53:04 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array triggered on the INTEGRAL alert for GRB 170710C 
(Mereghetti et al., GCN 21326) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 12 days 
post-burst. Our observations at 15 GHz on 2017 Jul 14.22, Jul 17.14, Jul 
18.14 and Jul 21.11 (UT) do not reveal any transient radio source within 
the INTEGRAL error circle (Mereghetti et al., GCN 21326), with 3sigma 
upper limits of 108 uJy, 90 uJy, 123 uJy and 108 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170711A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21463
SUBJECT: GRB 170711A: 15 GHz upper limits from AMI
DATE:    17/08/11 17:55:08 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170711A (D'Elia et al., GCN 21321) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2017 Jul 12.14, Jul 13.38, Jul 
16.29 and Jul 20.36 (UT) do not reveal any radio source at the XRT 
location (Beardmore et al., GCN 21323), with 3sigma upper limits of 186 
uJy, 96 uJy, 102 uJy and 183 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170714A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21464
SUBJECT: GRB 170714A: 15 GHz upper limits from AMI
DATE:    17/08/11 17:56:56 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170714A (D'Ai et al., GCN 21340) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2017 Jul 15.11, Jul 18.27, Jul 
20.23 and Jul 22.25 (UT) do not reveal any radio source at the XRT 
location (Evans et al., GCN 21341), with 3sigma upper limits of 279 uJy, 
172 uJy, 288 uJy and 210 uJy respectively. These upper limits are 
consistent with the results from previously-reported radio observations 
(Horesh et al., GCN 21352; Ricci et al., GCN 21360; Piro et al., GCN 
21424).

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170728A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21465
SUBJECT: GRB 170728A: 15 GHz upper limits from AMI
DATE:    17/08/11 18:11:16 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170728A (Cannizzo et al., GCN 21367) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2017 Jul 28.32, Jul 30.25, Aug 
01.27 and Aug 05.23 (UT) do not reveal any radio source at the XRT 
location (Goad et al., GCN 21368), with 3sigma upper limits of 141 uJy, 
131 uJy, 129 uJy and 133 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170728B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21466
SUBJECT: GRB 170728B: 15 GHz upper limits from AMI
DATE:    17/08/11 18:16:52 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for the 
short GRB 170728B (Cenko et al., GCN 21371) as part of the 4pisky 
program, and subsequent follow up observations were obtained up to 3 
days post-burst. Our observations at 15 GHz on 2017 Jul 29.00, Jul 
29.80, Jul 30.80 and Jul 31.76 (UT) do not reveal any radio source at 
the XRT location (Osborne et al., GCN 21377), with 3sigma upper limits 
of 258 uJy, 201 uJy, 171 uJy and 108 uJy respectively. This upper limit 
is consistent with the radio afterglow detection on 2017 Jul 29.81 
reported by Fong et al. (GCN 21395; much fainter than 300 uJy at 6 GHz).

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170813A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21468
SUBJECT: GRB 170813A: Swift detection of a burst
DATE:    17/08/13 01:30:09 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K. L. Page (U Leicester), J. A. Kennea (PSU), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report
on behalf of the Swift Team:

At 01:13:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170813A (trigger=767563).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 201.054, -5.469 which is 
   RA(J2000) = 13h 24m 13s
   Dec(J2000) = -05d 28' 07"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 30 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~6 sec before the trigger. 

The XRT began observing the field at 01:15:30.5 UT, 134.1 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
201.0572, -5.4909 which is equivalent to:
   RA(J2000)  = 13h 24m 13.73s
   Dec(J2000) = -05d 29' 27.1"
with an uncertainty of 2.8 arcseconds (radius, 90% containment). This
location is 79 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 2.73
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 5.59e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 143 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.04. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170813A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21469
SUBJECT: GRB 170813A: Enhanced Swift-XRT position
DATE:    17/08/13 07:32:14 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1507 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 170813A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 201.05759, -5.49079 which is equivalent
to:

RA (J2000): 13h 24m 13.82s
Dec (J2000): -05d 29' 26.9"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170813A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21470
SUBJECT: GRB 170813A: Swift-XRT refined Analysis
DATE:    17/08/13 14:41:34 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea
(PSU), B. Sbarufatti (INAF-OAB/PSU), S.L. Gibson (U. Leicester) and K.
L. Page (U Leicester) report on behalf of the Swift-XRT team:

We have analysed 10 ks of XRT data for GRB 170813A (Page et al. GCN
Circ. 21468), from 124 s to 39.0 ks after the  BAT trigger. The data
comprise 26 s in Windowed Timing (WT) mode (the first 9 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Osborne et
al. (GCN Circ. 21469).

The light curve can be modelled with an initial power-law decay with an
index of alpha=3.35 (+0.20, -0.18), followed by a break at T+796 s to
an alpha of 0.9 (+0.5, -0.8).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.8 (+/-0.4). The
best-fitting absorption column is  2.3 (+1.7, -1.3) x 10^21 cm^-2, in
excess of the Galactic value of 2.7 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.0 x 10^-11 (5.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.3 (+1.7, -1.3) x 10^21 cm^-2
Galactic foreground: 2.7 x 10^20 cm^-2
Excess significance: 2.5 sigma
Photon index:      1.8 (+/-0.4)

If the light curve continues to decay with a power-law decay index of
0.9, the count rate at T+24 hours will be 4.2 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-14 (2.2 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00767563.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170810A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21471
SUBJECT: GRB 170810A: AbAO optical upper limit
DATE:    17/08/13 19:29:38 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volnova  (IKI),  A. Pozanenko (IKI), R. Inasaridze (AbAO),  V. Ayvazian 
(AbAO),  O. Kvaratskhelia (AbAO), G. Inasaridze (AbAO), E. Mazaeva (IKI), 
I. Molotov (KIAM) report on behalf of larger GRB follow-up  collaboration:

We observed the field of the Swift  GRB 170810A (Gibson  et al., GCN 21450) 
with AS-32 (0.7m) telescope of Abastumani Observatory starting on August, 11 
(UT)  17:02:09. We obtained several unfiltered images of the field.   Within 
enhanced XRT error circle  (Goad et al., GCN   21451) we do not detect  the 
afterglow (Rebolo et al, GCN 21449; Gibson  et al., GCN 21450). Preliminary 
photometry of the field is following

Date        UT start         t-T0            Filter Exp.   OT   Err UpLim (3 
sigma)
                       (mid, days)                         (s)

2017-08-11 17:02:09  0.80915   CR     33*20  n/d  n/d 18.2


Photometry is based on nearby SDSS stars  (Lupton transformation)

SDSS id                           R_Lupton
J123141.98+033552.6 15.637 0.013
J123153.09+033552.7 14.800 0.012
J123154.00+033945.4 15.540 0.013




 


GRB_name: GRB170813A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21472
SUBJECT: GRB 170813A: RATIR Optical and NIR Observations
DATE:    17/08/13 20:13:16 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), JesÃºs
GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 170813A (Page, et al., GCN 21468) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/08 13.15 to 2017/08 13.18 UTC (2.48 to
3.06 hours after the BAT trigger), obtaining a total of 0.36 hours exposure
in the r and i bands and 0.15 hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle (Osborne, et al., GCN
21469), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the
following upper limits (3-sigma):

  r > 22.46
  i > 22.08
  Z > 20.23
  Y > 19.82
  J > 19.38
  H > 19.13

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170813A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21473
SUBJECT: GRB 170813A: Swift-BAT refined analysis
DATE:    17/08/14 01:33:07 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170813A (trigger #767563)
(Page, et al., GCN Circ. 21468).  The BAT ground-calculated position is
RA, Dec = 201.057, -5.527 deg which is
 RA(J2000)  =  13h 24m 13.7s
 Dec(J2000) = -05d 31' 37.4"
with an uncertainty of 3.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.

The mask-weighted light curve shows a initial ragged pulse with a fast rise starting
at about T-10 sec, peaking at T+3 sec and then decaying to near background by
T+40, followed by a second weaker pulse from T+40 to T+80 sec.
T90 (15-350 keV) is 75.5 +- 10.9 sec (estimated error including systematics).

The time-averaged spectrum from T-9.2 to T+78.9 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.17 +- 0.14.  The fluence in the 15-150 keV band is 1.9 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.64 sec in the 15-150 keV band
is 0.8 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/767563/BA/


GRB_name: GRB170813A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21480
SUBJECT: GRB 170813A: Swift/UVOT Upper Limits
DATE:    17/08/14 18:32:51 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170813A
144 s after the BAT trigger (Page et al., GCN Circ. 21468).
No optical afterglow consistent with the enhanced XRT position
(Osborne et al. GCN Circ. 21469)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           144          293          147         >20.1
u_FC               302          551          246         >19.8
white              144         6769          727         >21.4
v                  632        11867         1140         >19.3
b                  557         6564          432         >20.7
u                  302         6359          659         >20.4
w1                 682         6154          413         >19.9
m2                4314        12580         1090         >20.5
w2                5339        10954         1145         >20.4


GRB_name: GRB170813A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21491
SUBJECT: GRB 170813A: Fermi GBM observation
DATE:    17/08/15 21:25:46 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 01:13:25 UT on 13 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170813A (trigger 524279593/ 170813051),
which was also detected by the Swift/BAT (Page et al. 2017, GCN 21468).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 41
degrees.

The GBM light curve shows multiple pulses
with a duration (T90) of about 112 s (50-300 keV).
The time-averaged spectrum from T0-2.0 s to T0+23.6 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.52 +/- 0.11 and
the cutoff energy, parameterized as Epeak, is 547 +/- 85 keV.

The event fluence (10-1000 keV) in this time interval is
(8.09 +/- 0.51)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.7 s in the 10-1000 keV band
is 2.36 +/- 0.17 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
-- 
Suraj Poolakkil
Fermi GBM Graduate Research Assistant
Dept. of Space Science
University of Alabama in Huntsville


GRB_name: GRB170810A
Detection_method: VLA Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21492
SUBJECT: GRB 170810A: VLA Detection
DATE:    17/08/16 00:22:47 GMT
FROM:    Kate Alexander at Harvard  <kalexander@cfa.harvard.edu>

K. D. Alexander (Harvard), T. Laskar (NRAO / UC Berkeley), and E. Berger
(Harvard) report on behalf of a larger collaboration:

We observed the Swift GRB 170810A (Gibson et al., GCN 21450) at multiple
frequencies with the Karl G. Jansky Very Large Array (VLA) beginning 2017
August 12.77 UT (1.85 days after the burst). At a mean frequency of 7.1
GHz, we detect a radio source with a preliminary flux density of ~0.1 mJy.
In follow-up observations on 2017 August 15.03 UT the source had faded to
~half its original brightness, confirming this as the radio afterglow of
GRB 170810A.

The best-fit radio position is

RA (J2000) = 12:31:45.346
Dec (J2000) = +03:39:38.61

with an uncertainty of 0.4â€ in each coordinate. This is consistent with the
refined Swift/XRT position (Goad et al. GCN 21451) and the position of the
Swift/UVOT afterglow (LaPorte et al. GCN 21454).

We thank the VLA staff for rapidly executing these observations.


GRB_name: GRB170805A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21502
SUBJECT: GRB 170805A: AstroSat CZTI detection
DATE:    17/08/17 08:49:43 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of short GRB 170805A (Insight-HXMT detection: Ma X. et al, GCN Circ. 21421) in the 40-200 keV energy range. The light curve shows single peak emission at 14:38:34.70 UT, around ~0.7 s before the Insight-HXMT trigger. The measured peak count rate is 4917.1 counts/s above the background in combined data of four quadrants, with a total 22361 counts. The local mean background count rate was 372.9 counts/s. Using cumulative rates, we measure a T90 of 0.96 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170816A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21504
SUBJECT: GRB 170816A: Fermi GBM detection
DATE:    17/08/17 10:04:36 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

O.J. Roberts (USRA), C. Meegan (UAH) and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team:

"At 14:23:03.96 UT on 16 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170816A (trigger 524586188 / 170816599).
The on-ground calculated location, using the GBM trigger
data, is RA = 351.4, DEC = +19.1, with an uncertainty
of 2.2 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The initial angle from the Fermi LAT boresight to
the GBM best location is 97 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM triggered on an initial bright peak that
was followed ~1 s later by a slightly dimmer peak. The
total duration (T90) was about 2 s (50-300 keV).
The time-averaged spectrum from T0-0.064 to T0+1.600 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.5 +/- 0.1  and
the cutoff energy, parameterized as Epeak, is 1250.00 +/- 150.00 keV

The event fluence (10-1000 keV) in this time interval is
(4.0+/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.45 s in the 10-1000 keV band
is 7.3 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170816A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21517
SUBJECT: IPN Triangulation of GRB 170816A (short/hard)
DATE:    17/08/17 19:28:28 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, report:

A short-duration, hard-spectrum GRB 170816A was detected by
by Fermi (GBM; Roberts et al., GCN 21504), Konus-Wind, INTEGRAL
(SPI-ACS), and Swift (BAT), so far, at about 51784 s UT (14:23:04).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   350.841 (23h 23m 22s) +12.853 (+12d 51' 11")
  Corners:
   349.856 (23h 19m 25s) +13.372 (+13d 22' 19")
   352.036 (23h 28m 09s) +12.535 (+12d 32' 07")
   351.782 (23h 27m 08s) +12.294 (+12d 17' 38")
   349.591 (23h 18m 22s) +13.118 (+13d 07' 06")
  ---------------------------------------------
The error box area is 2650 sq. arcmin, and its maximum
dimension is 2.45 deg (the minimum one is 19 arcmin).
The Sun distance was 144 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170816_T51789/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170817A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21520
SUBJECT: GRB 170817A: Fermi GBM detection
DATE:    17/08/17 20:00:07 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE), C. Meegan (UAH) and A. Goldstein (USRA)
report on behalf of the Fermi GBM Team:

"At 12:41:06.47 UT on 17 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170817A (trigger 524666471 / 170817529).

The on-ground calculated location, using the GBM trigger
data, is RA = 176.8, DEC = -39.8 (J2000 degrees,
equivalent to 12 h 47 m, -39 d 48'), with an uncertainty
of 11.6 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 91 degrees.

The GRB light curve shows a weak short pulse
with a duration (T90) of about 2 s (50-300 keV).
The time-averaged spectrum from T0-0.512 s to 2.048 s is
well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.89 +/- 0.5 and
the cutoff energy, parameterized as Epeak, is 82 +/- 21 keV

The event fluence (10-1000 keV) in this time interval is
(2.3 +/- 0.4)E-07 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0-0.32 s in the 8-1000 keV band
is 1.9 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170817A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21528
SUBJECT: LIGO/Virgo G298048 - Update on Fermi/GBM GRB 170817A Analysis
DATE:    17/08/18 00:36:12 GMT
FROM:    Adam Goldstein at Fermi/GBM  <adam.michael.goldstein@gmail.com>

A. Goldstein (USRA), P. Veres (UAH), and A. von Kienlin (MPE) report on
behalf of the GBM-LIGO Group:
L. Blackburn (CfA), M. S. Briggs (UAH), J. Broida (Carleton College), E.
Burns (NASA/GSFC), J. Camp (NASA/GSFC), T. Dal Canton (NASA/GSFC), N.
Christensen (Carleton College), V. Connaughton (USRA), R. Hamburg (UAH), C.
M. Hui (NASA/MSFC), P. Jenke (UAH), D. Kocevski (NASA/MSFC), N. Leroy
(LAL), T. Littenberg (NASA/MSFC), J. McEnery (NASA/GSFC), R. Preece (UAH),
J. Racusin (NASA/GSFC), P. Shawhan (UMD), K. Siellez (GATech), L. Singer
(NASA/GSFC), J. Veitch (Glasgow), C. Wilson-Hodge (NASA/MSFC)


The GBM trigger (Connaughton et al., LVC GCN 21506), which we determine to
be a short GRB, occurred about 2 minutes before Fermi entered the South
Atlantic Anomaly. To estimate the False Alarm Rate (FAR) of a chance
coincident short GRB without using spatial information, we estimate the
rate of short GRBs (defined as t90 <= 2 s) triggered by GBM.  GBM has a
total of 351 triggered short GRBs over an estimated triggering livetime of
3.23e8 s. This results in a FAR of one per 10.7 days. A simple estimate of
the False Alarm Probability using only the temporal information of the two
signals is 2.2e-6 (~4.5 sigma).

The initial public report of the GRB (von Kienlin et al., GCN 21520)
contained the spectral information using the maximum of the GBM
localization posterior. Using the maximum of the updated LIGO/Virgo
localization posterior (LVC, LVC GCN 21513), which is consistent with the
GBM localization, we report the updated preliminary spectral information.

The estimated GRB duration is ~ 2 s and is best fit by a power-law function
with an exponential high-energy cutoff from T0-0.75 to T0+1.25 s.  The
power-law index is -0.88 +/- 0.44 and the cutoff energy, parametrized as
Epeak, is 128.0 +/- 48.7 keV. The event fluence (10-1000 keV) in this time
interval is (2.2 +/- 0.5)e-7 erg/cm^2, which we estimate to be near the
58th percentile of GBM-triggered short GRB fluences. The 64 ms peak photon
flux estimated starting at T0 is 3.6 +/- 1.1 ph/s/cm^2 (10-1000 keV).  The
corresponding spectrum over this peak flux interval is fit by an
exponential high-energy power law with index = -0.29 +/- 1.01 and Epeak =
124.2 +/- 52.6 keV.  The event peak energy flux (10-1000 keV) is (7.3 +/-
2.4)e-7 erg/s/cm^2.

Using this spectral information and the distance information provided by
the LVC (40 +/- 8 Mpc) we estimate that the isotropic energy release in
gamma-rays, Eiso ~ 4.3e46 erg in the 1 keV-10 MeV energy range and the
isotropic peak luminosity, Liso ~1.4e47 erg/s.

These results are preliminary and may be updated with further analysis.


GRB_name: GRB170817B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21540
SUBJECT: GRB 170817B: Fermi GBM detection
DATE:    17/08/18 04:12:29 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA) and C. Meegan (UAH) report on behalf of 
the Fermi GBM Team:

"At 21:47:34.43 UT on 17 August 2017, the Fermi Gamma-Ray 
Burst Monitor triggered and located GRB 170817B 
(trigger 524699259 / 170817908). The on-ground calculated 
location, using the GBM trigger data, is RA = 83.0, 
DEC = +50.1, with an uncertainty of 3.7 degrees (radius, 
1-sigma containment, statistical only; there is additionally 
a systematic error which we have characterized as a 
core-plus-tail model, with 90% of GRBs having a 3.7 deg error 
and a small tail suffering a larger than 10 deg systematic error. 
[Connaughton et al. 2015, ApJS, 216, 32] ).

The initial angle from the Fermi LAT boresight to
the GBM best location is 90 degrees.

The GBM triggered multiple short unresolvable pulses over a
total duration (T90) of 2.6 s (50-300 keV).
The time-averaged spectrum from T0+0.0 to T0+2.6 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.87 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 1120 +/- 228 keV

The event fluence (10-1000 keV) in this time interval is
(4.93 +/- 0.16)E-06 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 10.4 +/- 1.6 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB080905A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21550
SUBJECT: LIGO/VIRGO G298048: Swift UVOT detection and XRT upper limits
DATE:    17/08/18 07:24:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), J.A. Kennea (PSU), A.A. Breeveld (UCL-MSSL),
S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), E. Troja 
(NASA/GSFC/UMCP), P.T. O'Brien (U. Leicester), S.D. Barthelmy 
(NASA/GSFC), A.P. Beardmore (U. Leicester), D.N. Burrows (PSU),  G. 
Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), 
V.D'Elia(ASDC), S.W.K. Emery (UCL-MSSL), P. Giommi (ASI), C. Gronwall 
(PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien 
(GSFC/UMBC), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), J.A. 
Nousek (PSU), S.R. Oates (U. Warwick),  J.P. Osborne (U. Leicester), C. 
Pagani (U. Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), M. 
Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), 
M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), A. Tohuvavohu (PSU) report 
on behalf of the Swift team:

Swift has performed ToO observations of  the proposed optical
counterpart of LIGO/Virgo G298048 (Coulter et al. LVC GCN 21529).
We obtained 2 ks of data from 53.8 to 55.8 ks after the LVC trigger.

No X-ray source is detected at the location of the transient reported by 
Coulter et al. The 3-sigma upper limit at this location is 4.5e-3 
ct/sec. For a typical GRB spectrum this corresponds to 1.8e-13 
erg/cm^2/s (0.3-10 keV). Assuming a distance of 40 Mpc this corresponds 
to a 0.3-10 keV luminosity of 3.5e40 erg/s.

D'Avanzo et al (2014, MNRAS, 442, 2342) compiled the observed 2-10 keV 
luminosity at 11 hours post-trigger for a complete sample of 
Swift-detected short GRBs; these were typically of order 1e41-1e43 
erg/s. Our measurement corresponds to a 2-10 keV luminosity of 2.3e40 
erg/s, ~an order of magnitude fainter than all of the other sGRBs in 
that paper apart from GRB 080905. However those authors also showed a 
correlation between Eiso and X-ray afterglow luminosity, so given the 
low Eiso (Goldstein et al., LVC Circ. 21528) this may not be surprising.

The afterglow is detected in the Swift-UVOT data. Analysis is 
complicated by the nearby presence the galaxy NGC4993, but we obtain the 
following magnitudes:

Filter  Magnitude     Start time     Stop time
u      16.9 Â± 0.06    T0+53.8 ks     T0+54.5 ks
w1     17.74 Â± 0.09   T0+55.0 ks     T0+55.3 ks
m2     19.26 Â± 0.18   T0+54.5 ks     T0+55.0 ks
w2     19.12 Â± 0.17   T0+55.3 ks     T0+55.8 ks


We note that it is very unusual for an optical counterpart to be found 
but no X-ray counterpart, especially given the brightness of the optical 
counterpart. Therefore, if this object is a GRB afterglow, it is 
atypical compared to the sample of Swift-BAT triggered objects observed 
to date. We suggest therefore that the object may be a blue (i.e. 
lanthanide-free) kilonova.

This circular is an official product of the Swift team.

[GCN OPS NOTE(18aug17):  Per author's request, the trigger ID
in the Subject-line was corected from 298045 to 298048.]


GRB_name: GRB170818A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21573
SUBJECT: GRB 170818A: Fermi GBM detection
DATE:    17/08/18 19:25:23 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA) and C. Meegan (UAH) report on behalf of
the Fermi GBM Team:

"At 03:17:19.98 UT on 18 August 2017, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 170818A
(trigger 524719044 / 170818137). The on-ground calculated
location, using the GBM trigger data, is RA = 297.2,
DEC = +6.4, with an uncertainty of 11.5 degrees (radius,
1-sigma containment, statistical only; there is additionally
a systematic error which we have characterized as a
core-plus-tail model, with 90% of GRBs having a 3.7 deg error
and a small tail suffering a larger than 10 deg systematic error.
[Connaughton et al. 2015, ApJS, 216, 32] ).

The initial angle from the Fermi LAT boresight to
the GBM best location is 109 degrees.

The GBM triggered on a single pulse over a
total duration (T90) of about 0.6 s (50-300 keV).
The time-averaged spectrum from T0-0.06 to T0+0.51 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.37 +/- 0.32 and
the cutoff energy, parameterized as Epeak, is 80 +/- 9 keV

The event fluence (10-1000 keV) in this time interval is
(2.6 +/- 0.3)E-07 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 14 +/- 2 ph/s/cm^2.


GRB_name: GRB170817B
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21593
SUBJECT: GRB 170817B: Insight-HXMT observation
DATE:    17/08/19 13:32:35 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

Z. W. Li, J. Y. Liao, C. K. Li, X. B. Li, S. L. Xiong, C. Z. Liu,
X. F. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, X. Ma, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-08-17T21:47:34.00 (T0),
Insight-HXMT detected GRB 170817B (trigger ID: HEB170817908)
in a routine search of the data, which was also observed by
Fermi/GBM (Roberts et al. 2017, GCN 21540).

The Insight-HXMT light curve consists of multiple pulses
with a duration (T90) of 2.64 s measured from T0+0.40 s.
The 50-ms peak rate, measured from T0+0.40 s, is 6135.4 cnts/sec.
The total counts from this burst is 5353.1 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170817908_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The time-averaged spectrum from T0 to T0+3.60 s is
adequately fit by a Power Law model with spectral index = -1.60 +/- 0.05.
The energy fluence is (1.09 +/- 0.05)E-05 erg/cm^2 in 200 - 5000 keV in
this time interval.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170816A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21615
SUBJECT: GRB 170816A CALET Gamma-Ray Burst Monitor detection
DATE:    17/08/20 11:38:56 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

W. Ishizaki (ICRR), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170816A (Roberts et al., GCN Circ. 21504; Kozlova et al.,
GCN Circ. 21517) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 14:23:03.81 on 16 August 2017.  The burst signal was clearly seen by the SGM
instrument.

The light curve of the SGM shows a bright single peak.  The emission starts at
T+0.1 sec, peaks at T+0.3 sec and ends at T+0.5 sec.  The T90 duration measured
by the SGM data is 0.25 +- 0.13 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1186927993/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170817A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21618
SUBJECT: LIGO/Virgo G298048: optical observations of CHILESCOPE observatory
DATE:    17/08/20 14:24:47 GMT
FROM:    Alexei Pozanenko at IKI,Moscow  <grbgw.iki@gmail.com>

A. Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI),  P. Minaev 
(IKI), M. Krugov (AFIF) report on behalf of IKI-GW follow-up collaboration:

We observed  the field of  LIGO/Virgo trigger G298048 (LVC GCNs 21509, 
21513) and the error circle of GMB/Fermi short burst GRB 170817A 
(Connaughton et al., GCN 21506) with RC-1000 and ASA-500 telescopes of 
CHILESCOPE observatory located at W 70d 34m S20d 27m. The observations 
started on Aug 17 (UT) 23:17:16 in clear filter. The last image was 
recorded on 2017-08-18T00:59:48.

We cover central part of G298048 localization with typical limiting 
magnitude of 20m at 60 s exposure in each image. The covering map can be 
found in
http://grb.rssi.ru/GRB170817A/bayestar_RC1000%20coverage.png

The OT candidate found by Coulter et al. (LVC GCN 21529), the DLT17ck 
(Sheng Yang et al., GCN 21531) is out of the coverage in the first epoch 
of the observations.

We also cover northern part of GBM/Fermi  localization?  1-sigma 
containment, statistical only (Connaughton et al., GCN 21506). The 
coverage of the GBM localization is about 20%. Typical limiting 
magnitude of 17.5m at 60 s exposure in each image. The covering map can 
be found in
http://grb.rssi.ru/GRB170817A/GRB170817A_GBM_coverage_ASA500.png

The detailed investigation of the fields is underway.

We are grateful to the remote staff of the observatory for timely 
observations.


GRB_name: GRB170816A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21630
SUBJECT: Konus-Wind observation of GRB 170816A
DATE:    17/08/21 10:56:48 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The short/hard GRB 170816A
(Fermi GBM detection: Roberts et al., GCN 21504;
IPN triangulation: Kozlova et al., GCN 21517;
CALET Gamma-Ray Burst Monitor detection: Ishizaki et al., GCN 21615)
triggered Konus-Wind at T0=51789.108 s UT (14:23:09.108).

The burst light curve shows a bright, multi-peaked pulse
which started at ~T0-0.064 s and had a total duration of ~0.3 s.
A weaker count rate increase is also visible around ~T0+1.5 s
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
6.6(-2.4, +4.2)x10^-6 erg/cm2 and a 16-ms peak energy flux,
measured from T0+0.175s of (5.9 Â± 0.7)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range by a cutoff power-law
(CPL) function with the following model parameters:
the photon index alpha = -0.87(-0.36,+0.60),
and the peak energy Ep = 1156(-556,+1626) keV,
chi2 = 86/98 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta of -1.9,
chi2 = 86/97 dof.

The spectrum near the peak count rate (measured from T0+0.128
to T0+0.192 s) is best fit in the 20 keV - 15 MeV range
by the CPL function with the following model parameters:
the photon index alpha = +0.49(-0.50,+0.66),
and the peak energy Ep = 1339(-285,+462) keV,
chi2 = 17/19 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta of -1.6,
chi2 = 17/18 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170816_T51789/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.

[GCN OPS NOTE(21aug17): Per R.Hamberg's request, in the 2ndline
the Hamburg citation was changed to Roberts.]


GRB_name: GRB170822A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21640
SUBJECT: GRB 170822A: Swift detection of a burst
DATE:    17/08/22 09:32:56 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB),
K. L. Page (U Leicester), T. Sakamoto (AGU), B. Sbarufatti (PSU),
R. L. C. Starling (U Leicester) and E. Troja (NASA/GSFC/UMCP) report
on behalf of the Swift Team:

At 09:11:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170822A (trigger=768939).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 94.382, +55.019 which is 
   RA(J2000) = 06h 17m 32s
   Dec(J2000) = +55d 01' 07"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex 
structure with a duration of about 70 sec.  The peak count rate
was ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 09:14:34.2 UT, 163.2 seconds after
the BAT trigger. The position determined from promptly downlinked data
differs significantly from the on-board position, suggesting that the
XRT may have centroided on a cosmic ray; the initial XRT position
notice should be treated with caution. Using promptly downlinked data
we find a fading, uncatalogued X-ray source with an enhanced position:
RA, Dec 94.3869, 55.0040 which is equivalent to:
   RA(J2000)  = 06h 17m 32.86s
   Dec(J2000) = +55d 00' 14.5"
with an uncertainty of 2.0 arcseconds (radius, 90% containment). This
location is 54 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.91 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 2.6
(+2.37/-2.09) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 171 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.17. 

Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170817A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21641
SUBJECT: LIGO/Virgo G298048: CALET Observations
DATE:    17/08/22 09:36:51 GMT
FROM:    Takanori Sakamoto at Aoyama Gakuin U  <tsakamoto@phys.aoyama.ac.jp>

S. Nakahira (RIKEN), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U),
I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time
of G298048 (The LIGO Scientific Collaboration and the Virgo Collaboration,
GCN Circ. 21509).  No CGBM on-board trigger occurred at the time
of the event.  Based on the updated LVC localization sky map
(preliminary-LALInference.fits.gz), none of the probability area was in the
field-of-view of the CGBM/HXM.  However, 99% of the summed probability was
inside the field-of-view of the CGBM/SGM.  The CGBM/SGM boresight position
(R.A., Dec. = 223.8 deg, 43.4 deg) was 73 deg off-axis from the maximum LVC
probability location (The LIGO Scientific Collaboration and the Virgo Collaboration,
GCN Circ. 21527).

Based on the analysis of the light curve data with 0.125 sec time resolution
from -60 sec to 60 sec from the trigger time, we found no significant excess
around the trigger time in either the HXM (7-3000 keV) or the SGM (40 keV -28 MeV)
data.  The incident angle of SGM to the position of SSS17a (Coulter et al.,
GCN Circ. 21529) was 71 deg.  Assuming the association of GRB 170817A
(Connaughton et al., GCN Circ. 21506) and SSS17a, we estimated the upper
limit of the SGM.  The 7-sigma upper limit of SGM using alpha=-0.9 and Epeak=130 keV
(Goldstein et al., GCN Circ. 21528) is 5.5e-7 erg/cm2/s in the 10-1000 keV band
at 1 s exposure assuming no shielding by ISS structures.  This estimated upper
limit is at the similar level to the reported peak flux, 7.3e-7 erg/cm2/s, of
GRB 170817A by Fermi-GBM.  We further noticed that the position of SSS17a
was covered by the large structure of ISS at the time of the trigger.  Because
of this, the SGM sensitivity should be worse than what we reported above.
Therefore, it is consistent that no signal of GRB 170817A is seen by the SGM data.

The CALET Calorimeter (CAL) was operating in the high energy trigger mode at the
trigger time of G298048.  However, no LVC high probability region was included
in the CAL's field of view at the time of the trigger.


GRB_name: GRB170822A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21642
SUBJECT: GRB 170822A:BOOTES-5/JGT optical afterglow candidate
DATE:    17/08/22 11:12:19 GMT
FROM:    Juan Carlos Tello at IAA-CSIC  <jtello@iaa.es>

J. C. Tello, A. J. Castro-Tirado, R. Cunniffe, B.-B. Zhang, Y. Hu and A.
GonzÃ¡lez-RodrÃ­guez (IAA-CSIC), I. Carrasco (Univ. de Malaga), D. Hiriart,
W. H. Lee (UNAM), S. Jeong and I. H. Park (SKKU) and P. Kubanek (Inst. of
Physics, CZ) on behalf of a larger collaboration, report:

The 60 cm BOOTES-5/JGT at Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir (MÃ©xico) automatically responded in 7s (and 102s after the GRB onset) to
the Swift trigger of GRB 170822A (Melandri et al., GCN  21640).
The first unfiltered images (10 s exposures) were obtained at 09:13:38 UT
(mid exposure). At the position of the Swift  X-ray afterglow, we detect
the likely optical afterglow at a magnitude of 18.3 (comparing to
USNO-B1.0) and fading by 0.8 mag at 09:14:00 UT. The preliminary position
is RA (J2000) = 6:17:32.89, Dec (J2000) = +55:00:16.13 (+/- 0".5). Further
observations are being carried out. Spectroscopic observations are
encouraged.

We thank the staff at Observatorio AstronÃ³mico Nacional in San Pedro MÃ¡rtir
for its excellent support.

[GCN OPS NOTE(22aug17):  Per author's request, in the second line
the "after the alert" was changed to "after the GRB onset".]


GRB_name: GRB170822A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21643
SUBJECT: GRB 170822A: Enhanced Swift-XRT position
DATE:    17/08/22 14:29:01 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2226 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 170822A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 94.38672, +55.00424 which is equivalent
to:

RA (J2000): 06h 17m 32.81s
Dec (J2000): +55d 00' 15.3"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170822A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21647
SUBJECT: GRB 170822A: Swift-XRT refined Analysis
DATE:    17/08/22 17:25:14 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC),
J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU),
S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester) and A. Melandri
report on behalf of the Swift-XRT team:

We have analysed 8.8 ks of XRT data for GRB 170822A (Melandri et al.
GCN Circ. 21640), from 153 s to 19.2 ks after the  BAT trigger. The
data comprise 32 s in Windowed Timing (WT) mode (the first 7 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by
Beardmore et al. (GCN Circ. 21643).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.29 (+0.27, -0.23). At T+522 s  the decay
flattens to an alpha of -0.77 (+0.28, -0.35). The light curve breaks
again at T+1393 s to a decay with alpha=0.81 (+0.09, -0.11),  before a
final break at T+6591 s s after which the decay index is 1.89 (+0.37,
-0.14).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.84 (+/-0.08). The
best-fitting absorption column is  3.5 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.9 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.2 x 10^-11 (5.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.5 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^21 cm^-2
Excess significance: 6.6 sigma
Photon index:      1.84 (+/-0.08)

If the light curve continues to decay with a power-law decay index of
1.89, the count rate at T+24 hours will be 6.9 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.9 x
10^-13 (4.1 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00768939.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170822A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21649
SUBJECT: GRB 170822A: Swift/UVOT Upper Limits
DATE:    17/08/22 18:07:41 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and A. Melandri (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170822A
171 s after the BAT trigger (Melandri et al., GCN Circ. 21640).
No optical afterglow consistent with the XRT position
(Beardmore et al., GCN Circ. 21643)
and the optical position
(Tello et al., GCN Circ. 21642)
is detected in the initial UVOT exposures.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC        171          321          148         >20.4
white              529         1894          284         >21.3
v                      406         1936          165         >19.2
b                      504         1870          156         >20.2
u                      480         1845          156         >19.8
uvw1              455         1820          155         >19.7
uvm2              604         1101           39         >18.1
uvw2              381         1921          175         >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.17 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170822A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21651
SUBJECT: GRB 170822A: Swift-BAT refined analysis
DATE:    17/08/22 22:12:25 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
A. Melandri (INAF-OAB), D. M. Palmer (LANL),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170822A (trigger #768939)
(Melandri et al., GCN Circ. 21640).  The BAT ground-calculated position is
RA, Dec = 94.375, 55.000 deg which is
  RA(J2000)  =  06h 17m 29.9s
  Dec(J2000) = +54d 59' 59.0"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 12%.

The mask-weighted light curve shows a multi-peaked structure that starts at
~ T-15 s and ends at ~T+60 s. T90 (15-350 keV) is 64 +- 16 sec (estimated
error including systematics).

The time-averaged spectrum from T-15.62 to T+64.38 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.80 +- 0.09.  The fluence in the 15-150 keV band is 6.4 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+7.88 sec in the 15-150 keV band
is 4.2 +- 0.7 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/768939/BA/


GRB_name: GRB170822A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21652
SUBJECT: GRB 170822A: MITSuME Akeno Optical Observation
DATE:    17/08/23 07:15:59 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata@u.phys.nagoya-u.ac.jp>

K. L. Murata, Y. Saito, R. Itoh, Y. Tachibana, T. Yoshii, S. Harita, K.
Morita, T. Ozawa, H. Mamiya, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo
Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 170822A (Melandri et al.,
GCN Circular #21640) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan.

The observation started on 2017-08-22 16:27:38.15 UT . We did not find any
new point source within enhanced XRT circle (Evans et al., GCN Circular
#21643) in all three bands.
We obtained following limits for the magnitudes.


T0+[hour]    MID-UT      T-EXP[sec]         g'              Rc
       Ic
-------------------------------------------------------------------------------------------------------
~7.21        16:48:33.09      2280          >20.8        >20.1
 >18.9
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB170822A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21654
SUBJECT: GRB 170822A: AbAO optical upper limit
DATE:    17/08/23 13:14:20 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI),  R. Inasaridze (AbAO), A. Pozanenko (IKI),   A. 
Volnova  (IKI),   V. Ayvazian (AbAO),  O. Kvaratskhelia (AbAO), G. 
Inasaridze (AbAO), I. Molotov (KIAM) report on behalf of larger GRB 
follow-up  collaboration:

We observed the field of the Swift  GRB 170822A   (Melandri et al.,
GCN  21640)) with AS-32 (0.7m) telescope of Abastumani Observatory 
starting on August, 22 (UT) 22:43:12. We obtained several unfiltered 
images of the field.   Within enhanced XRT error circle  (Beardmore et 
al., GCN   21643) we do not detect  the afterglow candidate (Tello et 
al, GCN 21642). Preliminary photometry of the field is following

Date        UT start  t-T0     Filter Exp.   OT   Err UpLim (3 sigma)
                       (mid, days)     (s)

2017-08-22 22:43:12  0.58255   CR     32*60  n/d  n/d 22.2

Photometry is based on nearby USNO-B1.0 stars R2 magnitudes
USNO-B.1_id  R2
1450-0165651 15.44
1450-0165657 15.54
1450-0165669 16.19
1450-0165558 16.58
1450-0165549 15.60
1450-0165573 15.28
1449-0164981 16.05

A finding chart can be found at 
http://grb.rssi.ru/GRB170822A/GRB170822A_AAO_170822+Bootes-OT.png


GRB_name: GRB170822A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21655
SUBJECT: GRB 170822A: RATIR Optical and NIR Observations
DATE:    17/08/23 13:59:54 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara
(UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and
Vicki Toy (UMD) report:

We observed the field of GRB 170822A (Melandri et al., GCN Circ. 21640) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/08 23.44 to 2017/08 23.48 UTC (25.45
to 26.38 hours after the BAT trigger), obtaining a total of 0.69 hours
exposure in the r and i bands and 0.30 hours exposure in the Z,
Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with the USNO-B1 
and 2MASS catalogs, we obtain the following upper limits (3-sigma):

 r > 23.37
 i > 22.87
 Z > 21.99
 Y > 21.56
 J > 21.28
 H > 20.82

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

The bright but rapidly-fading optical transient reported by Tello et al. 
(GCN Circ. 21642) is not seen in our images.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro 
MÃ¡rtir.


GRB_name: GRB170823A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21666
SUBJECT: GRB 170823A: Swift detection of a burst
DATE:    17/08/23 22:30:42 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

E. Troja (NASA/GSFC/UMCP), A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC),
K. L. Page (U Leicester) and A. Tohuvavohu (PSU) report on behalf of
the Swift Team:

At 22:16:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170823A (trigger=769177).  Swift did not slew due to the Sun 
observing constraint. The BAT on-board calculated location is 
RA, Dec 188.719, +35.582 which is 
   RA(J2000) = 12h 34m 53s
   Dec(J2000) = +35d 34' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 60 sec.  The peak count rate
was ~4900 counts/sec (15-350 keV), at ~11 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 18:03 UT on 2017 October 17. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170823A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21678
SUBJECT: GRB 170823A: Swift-BAT refined analysis
DATE:    17/08/24 15:35:39 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
E. Troja (NASA/GSFC/UMCP), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170823A (trigger #769177)
(Troja et al., GCN Circ. 21666).  The BAT ground-calculated position is
RA, Dec = 188.713, 35.549 deg which is
  RA(J2000)  =  12h 34m 51.1s
  Dec(J2000) = +35d 32' 58.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 79%.

The mask-weighted light curve shows a multi-peaked light curve that starts at
~ T0 and ends at ~T+90 s. T90 (15-350 keV) is 69.4 +- 11.7 sec (estimated error
including systematics).

The time-averaged spectrum from T-0.36 to T+87.31 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.06 +- 0.09.  The fluence in the 15-150 keV band is 2.6 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+21.40 sec in the 15-150 keV band
is 3.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/769177/BA/


GRB_name: GRB170822A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21679
SUBJECT: Konus-Wind observation of GRB 170822A
DATE:    17/08/24 15:43:32 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, soft-spectrum GRB 170822A
(Swift-BAT detection: Melandri et al., GCN Circ. 21640)
triggered Konus-Wind at T0=33111.022 s UT (09:11:51.022).

The burst light curve shows a multipeaked structure
which starts at ~T0-10.5 s and has a total duration of ~62 s.
The emission is seen up to ~1 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170822_T33111/

As observed by Konus-Wind, the burst
had a fluence of 8.57(-0.76,+0.88)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.266 s,
of 1.66(-0.60,+0.60)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+57.6 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.20(-0.38,+0.48)
and Ep = 70(-12,+12) keV (chi2 = 57/62 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.4
(chi2 = 55/61 dof).

The spectrum near the maximum count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
with  alpha = -1.17(-0.26,+0.30)
and Ep = 90(-11,+13) keV (chi2 = 51/61 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.8
(chi2 = 51/60 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170825A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21689
SUBJECT: GRB 170825A: AGILE/MCAL Detection
DATE:    17/08/25 12:23:09 GMT
FROM:    Francesco Verrecchia at ASDC  <francesco.verrecchia@ssdc.asi.it>

M. Cardillo, A.Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor
Vergata), N. Parmiggiani (INAF/IASF-Bo), F. Longo (Univ. Trieste and INFN
Trieste), F. Verrecchia (SSDC and INAF/OAR), A. Bulgarelli (INAF/IASF-Bo),
C. Pittori (SSDC and INAF/OAR), M. Pilia (INAF/OA-Cagliari), G. Piano
(INAF/IAPS), I. Donnarumma (ASI), G. Minervini, A. Argan, Y. Evangelista
(INAF/IAPS), F. Lucarelli (SSDC and INAF/OAR),  A. Zoli, V. Fioretti, F.
Fuschino (INAF/IASF-Bo), A. Trois (INAF/OA-Cagliari) M. Marisaldi
(INAF/IASF-Bo and Bergen University), A. Giuliani (INAF/IASF-Mi), report
on behalf of the AGILE Team:

The AGILE Mini-CALorimeter (MCAL) detected a short burst at
T0 = 2017-08-25 02:19:49 UTC included in the acquisition (following an
internal trigger) started at T1=02:21:27 UTC and ended at 02:21:34 UTC.
The MCAL light curve shows a sharp single peak, that lasted about 32 ms
and released a total number of ~48 counts at E>400 keV in the detector,
above an average background rate of 19 counts/32ms.

The AGILE-MCAL detector has a full solid angle acceptance, and is
operational in the range 0.4 - 100 MeV.


GRB_name: GRB170816A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21695
SUBJECT: LIGO/Virgo G297595: INTEGRAL pointed follow-up observations
DATE:    17/08/25 14:33:57 GMT
FROM:    Volodymyr Savchenko at APC,Paris  <savchenk@apc.in2p3.fr>

V. Savchenko (ISDC, University of Geneva, CH)
on behalf of the INTEGRAL group:
C. Ferrigno, E. Bozzo ((ISDC, University of Geneva, CH),
E. Kuulkers (ESTEC/ESA, The Netherlands),
S. Mereghetti (IASF-Milano, Italy),
T. J.-L. Courvoisier (ISDC, University of Geneva, CH)
J. Chenevez, S. Brandt (DTU - Denmark)
R. Diehl (MPE-Garching, Germany)
L. Hanlon (UCD, Ireland)
P. Laurent (APC, Saclay/CEA, France), D. Gotz (DRF/Irfu/DAp Saclay/CEA)
J.P. Roques, E. Jourdain (IRAP, France)
P. Ubertini, A. Bazzano, J. Rodi (IAPS-Roma, Italy)
A. Lutovinov, R. Sunyaev (IKI, Russia)

INTEGRAL is an observatory with multiple instruments: a gamma-ray
spectrometer (20 keV -4 MeV, SPI), an imager (15 keV - 2 MeV, IBIS),
an X-ray monitor (3-25 keV, JEM-X), and an optical monitor (V band,
OMC). Our group requested and obtained pointed follow-up observations
of the LIGO/Virgo candidate BBH merger G297595 (GCN 21474).

The INTEGRAL follow-up observation was centered on RA=41.07
Dec=-45.49, close to the peak of the LIGO/Virgo localization
probability, taking into account observational constrains. This
observation spanned from 2017-08-16 at 10:04 to 2017-08-17 at 18:19
(starting about 47 hours after the LIGO/Virgo event), with a maximum
on-source time of 97.5 ks (depending on the instrument).

IBIS and SPI observed more than 92% of the of LIGO/Virgo localization
in the combined observation mosaic. JEM-X covered about 79%, owing to
its smaller Field of View.  INTEGRAL provides the most stringent
constraint on any possible emission associated with G297595, above 80
keV.  We searched IBIS/ISGRI and JEM-X data for new point sources in
the whole 90% LIGO/Virgo localization region, and did not find any. We
set the following 3-sigma upper limits for the average flux:

JEM-X:

3-10 keV: 2.0 mCrab (3.2e-11  erg/cm2/s )
10-25 keV: 1.0 mCrab (1.1e-11  erg/cm2/s )

ISGRI:

20-80 keV: 3.3 mCrab (4.9e-11 erg/cm2/s)
80-300 keV: 13.1 mCrab (1.5e-10 erg/cm2/s)


In the case of ISGRI (JEM-X), 82% (59%) of the of LIGO/Virgo
localization is covered with sensitivity no more than factor two worse
than the best.

During these observation online INTEGRAL/IBAS system identified
several weak triggers. After offline inspection, we consider these
triggers unrelated noise.

INTEGRAL/IBAS online search in the SPI-ACS identified a bright
GRB170816A on 2017-08-16 at 14:22:58. The location of this GRB is
inconsistent with the LIGO/Virgo 90% localization (GCN 21504, 21517).

Finally, the BNS merger G298048 (GCN 21509, 21513) candidate
counterpart (GRB 170817A, GCN 21506, 21520) was detected in the
INTEGRAL data during this observation, as reported in GCN 21507.

We have also inspected PICsIT spectral-timing data (200 - 2600 keV)
and did not find any evidence for significant variability.

Further analysis is ongoing.

We acknowledge the essential support by the teams at ESAC and ESOC for
the scheduling of this follow-up observation.


GRB_name: GRB170822A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21702
SUBJECT: GRB 170822A: AstroSat CZTI detection
DATE:    17/08/25 19:15:22 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of short GRB 170822A (Swift detection: Melandri A. et al, GCN Circ. 21640) in the 40-200 keV energy range. The light curve shows multiple peaks of emission with the strongest peak at 09:11:52.0 UT, around 1 s after the Swift/BAT trigger. The measured peak count rate is 163.1 counts/s above the background in combined data of four quadrants, with a total 369 counts. The local mean background count rate was 399.0 counts/s. Using cumulative rates, we measure a T90 of 62.3 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170820A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21705
SUBJECT: GRB 170820A CALET Gamma-Ray Burst Monitor detection
DATE:    17/08/25 23:59:26 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

M. L. Cherry (LSU), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa,
S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170820A (Konus-Wind trigger time on 11:12:06.755 UT)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 11:12:05.10 on
20 August 2017.  The burst signal was seen by the all CGBM instruments.

The light curve of the SGM shows a single peak.  The emission starts at
T+1 sec, peaks at T+4.5 sec and ends at T+9 sec.  There is a hint of the
peaked emission at T+8 sec.  The T90 duration measured by the
SGM data is 4.1 +- 0.5 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1187262128/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.

[GCN OPS NOTE(25aug17): Per author's request, the URL was corrected
from 1187301799 to 1187262128.]


GRB_name: GRB170826A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21715
SUBJECT: GRB 170826A: Fermi GBM detection
DATE:    17/08/26 19:00:17 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Poolakkil (UAH), E. Bissaldi (Politecnico & INFN Bari) and C. Meegan
(UAH)
report on behalf of the Fermi GBM Team:

"At 08:51:07.51 UT on 26 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170826A (trigger 525430272/ 170826369).

The on-ground calculated location, using the GBM trigger
data, is RA = 82.4, DEC = 32.8, with an uncertainty
of 7.2 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 101
degrees.

The GBM triggered on a single pulse over a
total duration (T90) of about 0.2 s (50-300 keV).
The time-averaged spectrum from T0-0.2 to T0+0.1 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.05 +/- 0.11 and
the cutoff energy, parameterized as Epeak, is 685 +/- 236 keV.

The event fluence (10-1000 keV) in this time interval is
 (8.2 +/- 0.6)E-07 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.1 s in the 10-1000 keV band
is 18.6 +/- 2.1 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

-- 
Suraj Poolakkil
Fermi GBM Graduate Research Assistant
Dept. of Space Science
University of Alabama in Huntsville


GRB_name: GRB170826B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21717
SUBJECT: GRB 170826B: Fermi GBM detection
DATE:    17/08/27 01:48:55 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 19:38:56.48 UT on 26 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170826B (trigger 525469141/ 170826819).

The on-ground calculated location, using the GBM trigger
data, is RA = 327.7, DEC = -31.8, with an uncertainty
of 1 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high fluence
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM
in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground best location is 110 degrees.

The GBM light curve shows multiple overlapping pulses
with a duration (T90) of about 11 s (50-300 keV).
The time-averaged spectrum from T0-2.0 to T0+20.5 s is
best fit by a Band function with Epeak = 385 +/- 24 keV,
alpha = -0.98 +/- 0.02, and beta = -2.24 +/- 0.10.

The event fluence (10-1000 keV) in this time interval is
(3.592 +/- 0.052)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.0 s in the 10-1000 keV band
is 25.4 +/- 0.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

-- 
Suraj Poolakkil
Fermi GBM Graduate Research Assistant
Dept. of Space Science
University of Alabama in Huntsville


GRB_name: GRB170827A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21718
SUBJECT: GRB 170827A: Swift detection of a burst
DATE:    17/08/27 05:25:35 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

F. E. Marshall (NASA/GSFC), A. D'Ai (INAF-IASFPA),
K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 05:12:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170827A (trigger=769567).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 276.180, -40.220 which is 
   RA(J2000) = 18h 24m 43s
   Dec(J2000) = -40d 13' 11"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical for an image trigger, the
immediately-available BAT lightcurve shows no obvious variation. 

The XRT began observing the field at 05:14:32.5 UT, 124.1 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 276.1508, -40.2016 which is equivalent to:
   RA(J2000)  = +18h 24m 36.19s
   Dec(J2000) = -40d 12' 05.8"
with an uncertainty of 4.9 arcseconds (radius, 90% containment). This
location is 104 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to determine the
column density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 4.23e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 133 seconds after the BAT trigger. Only partial
images are available and neither the 2.7'x2.7' sub-image nor the 8'x8'
region for the list of sources generated on-board covers the XRT error
circle. Analysis of any potential afterglow will have to await further
data. 

Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170827A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21721
SUBJECT: GRB 170827A: REM optical/NIR observations
DATE:    17/08/27 09:28:32 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo, D. Fugazza, S. Covino (INAF/OAB) report on behalf of the REM team:

We observed the field of the short GRB 170827A (Marshall et al., GCN 21718) with the 60-cm robotic 
telescope REM located at the La Silla Observatory (Chile). The observations started at 05:14:24 UT, 
116 seconds after the burst, and were carried out simultaneously in the g, r, i, z and H bands.

A preliminary photometry of the first co-added images indicates that no obvious afterglow candidate 
is detected within the Swift/XRT error circle (Marshall et al., GCN 21718) down to the following 3sigma 
limiting AB magnitudes:

r > 19.5 at T-T0 = 720s
H > 17.5 at T-T0 = 585s


Magnitudes are in the AB system and have been calibrated with respect to the 2MASS (H-band) 
and APASS (r-band) catalogues.


GRB_name: GRB170827A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21722
SUBJECT: GRB 170827A: Swift/UVOT Upper Limits
DATE:    17/08/27 15:15:10 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170827A
134 s after the BAT trigger (Marshall et al., GCN Circ. 21718).
No optical afterglow consistent with the XRT position
(Marshall et al. GCN Circ. 21718)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and a subsequent short exposure are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           134          284          147         >19.8
u                  292          298            6         >17.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.11 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170827A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21724
SUBJECT: GRB 170827A, Swift-BAT refined analysis
DATE:    17/08/27 16:58:00 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+509 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170827A (trigger #769567)
(Marshall et al. GCN Circ. 21718).  The BAT ground-calculated position is
RA, Dec = 276.189, -40.202 deg which is
  RA(J2000)  =  18h 24m 45.3s
  Dec(J2000) = -40d 12' 07.9"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.

The mask-weighted light curve shows a weak pulse that starts at ~T+20 s
and ends at ~T+140 s. T90 (15-350 keV) is 94.0 +- 12.5 sec (estimated error
including systematics).

The time-averaged spectrum from T+19.1 to T+138.9 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.29 +- 0.18.  The fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+67.13 sec in the 15-150 keV band
is 0.4 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/769567/BA/


GRB_name: GRB170823A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21727
SUBJECT: GRB 170823A: TAROT Calern observatory optical observations
DATE:    17/08/27 22:01:31 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:

We imaged the field of GRB 170823A detected by SWIFT
(trigger 769177) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 28s after the GRB trigger
(18s after the notice). The elevation of the field decreased from
3 degrees above horizon and weather conditions
were very good.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+28s to t0+88s : Rlim = 15.1

The second image is 30.0s exposure in tracking mode:
t0+101s to t0+131s : Rlim = 15.1

We co-added a series of exposures:
t0+101s to t0+395s : Rlim = 16.8

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB170827A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21728
SUBJECT: GRB 170827A: ePESSTO NTT afterglow candidate
DATE:    17/08/28 02:33:35 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

J. Lyman (Univ. of Warwick), D. Homan (Univ of Edinburgh), P. D'Avanzo (INAF-OAB), Patricia Schady (MPE Garching), 
K. E. Heintz (DARK/NBI), E. Palazzi (INAF-IASFBo), L. Galbany (Univ. de Chile), J. Anderson (ESO), C. Inserra (Southampton), 
E. Kankare (QUB), K. Maguire (QUB), S. Smartt (QUB), K. W. Smith (QUB), O. Yaron (Weizmann), D. Young (QUB), 
I. Manulis (Weizmann) report:


We observed the field of GRB 170827A (Marshall et al., GCN 21718) under the extended Public ESO Spectroscopic Survey for 
Transient Objects (ePESSTO; see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org ). The observations were performed on 
the ESO New Technology Telescope at La Silla with the SofI and EFOSC2 instrument in imaging mode starting from 2017-08-28 
at 00:47:05 UT (i.e. 19.58 hours from the burst). Observations were carried out with the Z, J, R and I filters.

Within the XRT error circle (Marshall et al., GCN 21718) we detect an object at the following coordinates:

RA(J2000), Dec(J2000) = 18:24:36.14, -40:12:06.3 

(+/- 0.5"). The object has a magnitude R~21.5 (based on preliminary photometry calibrated against the USNOB1 catalogue) at 
T-T0 = 20.08 hours. We cannot make any statement about variability at this time.We also notice the presence of a fainter object 
about 2.4" West. 


GRB_name: GRB170827A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21729
SUBJECT: GROND observations of GRB170827A
DATE:    17/08/28 09:40:33 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

P. Schady (MPE Garching) reports

I observed the field of GRB 170827A (Swift trigger 769567; Marshall et
al., GCN #21718) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 00:44 UT on 28-08-2017, 19.5 hours after the GRB
trigger. They were performed at an average seeing of 1.5" and at an
average airmass of 1.0.

A point source is present within the 4.9" Swift-XRT error circle (Marshall
et al., GCN #21718) in the g'r'i'z' GROND images, consistent with the
ePESSTO position reported by Lyman et al. (GCN #21728).

Based on a total exposure time of 36 min in g'r'i'z' and 30 min in JHK,
the estimated preliminary magnitudes and upper limits (all in AB system)
are

g' = 22.8 +/- 0.1 mag
r' = 21.9 +/- 0.1 mag
i' = 21.6 +/- 0.1 mag
z' = 21.4 +/- 0.1 mag
J > 21.1 mag
H > 20.6 mag
K > 20.1 mag

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.09 mag in the
direction of the burst (Schlafly & Finkbeiner 2011).

A second fainter source is also detected within the XRT error circle at
around 2.3" west of the ePESSTO afterglow candidate. No statement can be
made at this time on the variability of either source.

I acknowledge the excellent help provided by the support astronomer in La
Silla, Markus Rabus, in obtaining these data.


GRB_name: GRB170827A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21730
SUBJECT: GRB 170827A: Swift-XRT refined Analysis
DATE:    17/08/28 13:23:16 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@ifc.inaf.it>

A. D'Ai (IASF-PA), V. D'Elia (ASDC), F. E. Marshall (NASA/GSFC) reports
on behalf of the Swift-XRT team:

We have analysed 1.1 ks of XRT data for GRB 170827A (Marshall et al.
GCN Circ. 21718), from 113 s to 17.3 ks after the  BAT trigger. The
data comprise 165 s in Windowed Timing (WT) mode (the first 9 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode.

The initial light curve from T0+130s to T0+295s can be modelled with a
power-law decay with a decay index of alpha=1.19 (+/-0.08). In the
following observation at T0+16.1 ks the afterglow is not detected with
a 3-sigma upper limit of 1.6 x 10^-2 count^-1 s^-1. 

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.23 (+0.06, -0.05). The
best-fitting absorption column is  1.46 (+/-0.15) x 10^21 cm^-2, in
excess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.0 x 10^-11 (4.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:   1.46 (+/-0.15) x 10^21 cm^-2
Galactic foreground: 1.2 x 10^21 cm^-2
Excess significance: 3.0 sigma
Photon index:   2.23 (+0.06, -0.05)

Given the lack of detection in the second observation, no reliable
estimate of the X-ray count rate for the following days is possible.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00769567.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170826A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21734
SUBJECT: IPN Triangulation of GRB 170826A (short)
DATE:    17/08/28 18:38:45 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team, and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
report:

The short GRB 170826A (Poolakkil et al., GCN Circ. 21715) was detected
by Fermi (GBM trigger 525430272), Konus-Wind, and INTEGRAL (SPI-ACS)
at about 31868 s UT (08:51:08).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    64.338 (04h 17m 21s) +21.074 (+21d 04' 26")
  Corners:
    65.488 (04h 21m 57s) +16.011 (+16d 00' 39")
    63.331 (04h 13m 19s) +25.959 (+25d 57' 32")
    63.050 (04h 12m 12s) +26.051 (+26d 03' 05")
    65.226 (04h 20m 54s) +16.124 (+16d 07' 27")
  ---------------------------------------------
The error box area is 2.3 sq. deg, and its maximum
dimension is 10.29 deg (the minimum one is 13.56 arcmin).
The Sun distance was 87 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170826_T31868/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170827B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21735
SUBJECT: IPN Triangulation of GRB 170827B (short)
DATE:    17/08/28 19:07:06 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team, and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, report:

The short GRB 170827B was detected by Fermi (GBM trigger 525555489),
Konus-Wind, INTEGRAL (SPI-ACS), and Swift (BAT)
at about 70684 s UT (19:38:04).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Corners:
    55.251 (03h 41m 00s) -21.923 (-21d 55' 22")
    53.829 (03h 35m 19s) -23.046 (-23d 02' 44")
     5.177 (00h 20m 42s) -74.042 (-74d 02' 32")
     7.290 (00h 29m 10s) -72.425 (-72d 25' 28")
  ---------------------------------------------
The error box area is 74 sq. deg, and its maximum
dimension is 99.7 deg (the minimum one is 77.2 arcmin).
The Sun distance was 104 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170827_T70686/IPN

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB170826B
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21739
SUBJECT: GRB 170826B: Insight-HXMT detection
DATE:    17/08/29 03:49:05 GMT
FROM:    Zhengwei Li at IHEP  <lizw@ihep.ac.cn>

Z. W. Li, J. Y. Liao, C. K. Li, X. B. Li, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:


During the commissioning phase, at 2017-08-26T19:38:58.00 (T0),
Insight-HXMT detected GRB 170826B (trigger ID: HEB170826818)
in a routine search of the data, which was also observed by
Fermi/GBM (Poolakkil et al, GCN Circ.21717).


The Insight-HXMT light curve consists of multiple pulses
with a duration (T90) of 10.12 s measured from T0-0.46s.
The 500-ms peak rate, measured from T0-0.46 s, is 2948.6 cnts/sec.
The total counts from this burst is 23373.3 counts.


URL_LC: http://www.hxmt.org/images/GRB/HEB170826818_lc.jpg


All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.


The time-averaged spectrum from T0-1.00 to T0+9.00 s is
adequately fit by a Power Law model with spectral index = -2.03 +/- 0.04 . 
The energy fluence is (1.46 +/- 0.06)E-05 erg/cm^2 in 200 - 5000 keV in 
this time interval.


The analysis results presented above are preliminary;
final results will be published elsewhere.


Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome.




--

Sincerely Yours,
Zhengwei Li,
Key Laboratory of Particle Astrophysics,
Institute of High Energy Physics, 
Chinese Academy of Sciences, Beijing China
TEL:15210983070 E-mail:lizw@ihep.ac.cn


GRB_name: GRB170827A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21743
SUBJECT: GRB170827A: Further GROND follow-up observations
DATE:    17/08/29 07:29:05 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

P. Schady (MPE Garching) reports

I re-observed the field of GRB 170827A (Swift trigger 769567; Marshall et
al., GCN #21718) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) on 29-08-2017, 1.8 days after the GRB trigger and 1
day after the first set of GROND observations (Schady, GCN #21729) .
Observations were performed at an average seeing of 1.4" and at an average
airmass of 1.0.

The two point sources detected within the 4.9" XRT error circle (Marshall
et al., GCN #21718) in the first epoch of GROND observations (Schady, GCN
#21729) are still seen in the second epoch of GROND observations and they
remain at the same magnitude. Neither of these sources are therefore
likely to be the optical counterpart of GRB 170827A.

I acknowledge the excellent help provided by the support astronomer in La
Silla, Markus Rabus, in obtaining these data.


GRB_name: GRB170817A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21747
SUBJECT: LIGO/Virgo G298048: ALMA observations 
DATE:    17/08/29 12:37:56 GMT
FROM:    Rhaana Starling at U.of Leicester  <rlcs1@leicester.ac.uk>

S. Schulze (Weizmann Institute of Science), S. Kim (PUC Chile), S. Martin (JAO), F. E. Bauer (PUC Chile), M. Bremer (IRAM), S. Campana (INAF Brera), Z. Cano (IAA Granada), J. Corral-Santana (ESO Chile), P. D'Avanzo (INAF Brera), C. De Breuck (ESO), I. de Gregorio-Monsalvo (JAO), M. de Pasquale (Istanbul University), J. P. U. Fynbo (Dark Cosmology Centre), D. Garcia-Appadoo (JAO), D. Hartman (U. Clemson), J. Hjorth (Dark Cosmology Centre), P. Jakobsson (U. Iceland), D. A. Kann (IAA Granada), T. Kruehler (MPE Garching), R. Lekshmi (ARIES), A. J. Levan (U Warwick), A. Lundgren (JAO), D. Malesani (Dark Cosmology Centre), M. Michalowski (Adam Mickiewicz University), B. Milvang-Jensen (Dark Cosmology Centre), K. Misra (ARIES), S. R. Oates (U. Warwick), R. Sanchez-Ramirez (IAA Granada), M. Sparre (Heidelberg Institute for Theoretical Studies), R. L. C. Starling (U. Leicester), N. R. Tanvir (U. Leicester), C. C. Thoene (IAA Granada) and D. J. Watson (Dark Cosmology Centre) report:

We have used the Atacama Large Millimeter/submillimeter Array, ALMA, to observe the field of LIGO/Virgo candidate G298048 (The LIGO Scientific Collaboration and the Virgo Collaboration GCN Circ. 21509) and GRB 170817A (Connaughton et al. GCN Circ. 21506; Svinkin et al. GCN Circ. 21515), centered on the position of the optical transient reported in Coulter et al. (GCN Circ. 21529).

Observations were taken at four epochs: 2017-08-18, 2017-08-20, 2017-08-21 and 2017-08-25 and have been carried out in the B7 band centred at 338.5 GHz (central wavelength 0.89 mm). The field of view covered an area of 18.3 arcsec. Data processing is underway.

We thank ALMA for their excellent support.


GRB_name: GRB170826B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21753
SUBJECT: IPN Triangulation of GRB 170826B
DATE:    17/08/29 16:44:47 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:


The long-duration GRB 170826B (Poolakkil et al., GCN 21717) was detected
by Fermi (GBM trigger 525469141), Konus-Wind, INTEGRAL (SPI-ACS),
Insight (HXMT, Li et al., GCN 21739), Mars-Odyssey (HEND),
and Swift (BAT) at about 70736 s UT (19:38:56).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   331.259 (22h 05m 02s) -33.916 (-33d 54' 58")
  Corners:
   329.379 (21h 57m 31s) -34.070 (-34d 04' 13")
   329.998 (21h 59m 59s) -34.318 (-34d 19' 05")
   333.019 (22h 12m 04s) -33.643 (-33d 38' 34")
   332.435 (22h 09m 44s) -33.458 (-33d 27' 30")
  ---------------------------------------------
The error box area is 3108 sq. arcmin, and its maximum
dimension is 3.1 deg (the minimum one is 20 arcmin).
The Sun distance was 155 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170826_T70742/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170830A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21761
SUBJECT: GRB 170830A: MAXI/GSC detection
DATE:    17/08/30 05:53:04 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

T. Yoneyama (Osaka U.), S. Nakahira  (RIKEN), S. Sugita (Tokyo Tech),
T. Mihara, M. Sugizaki, M. Serino,
W. Iwakiri, M. Shidatsu, M. Matsuoka (RIKEN), 
H. Negoro, M. Nakajima, T. Kawase, A. Sakamaki (Nihon U.),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA),
N. Kawai, T. Yoshii, Y. Tachibana, S. Harita, Y. Muraki, K. Morita (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka, T. Hashimoto (AGU), 
H. Tsunemi, (Osaka U.), 
Y. Ueda, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), 
Y. Tsuboi, Y. Nakamura, R. Sasaki, H. Kawai  (Chuo U.), 
M. Yamauchi, C. Hanyu, K, Hidaka (Miyazaki U.), 
T. Kawamuro (NAOJ), 
K. Yamaoka (Nagoya U.) 


GRB 170830A: MAXI/GSC detection

 The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at UT 03:15:29 UT on 2017 August 30. 
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (267.244 deg, -2.000 deg) = (17 48 58, -02 00 00) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.09 deg and 0.05 deg, respectively. 
The roll angle of long axis from the north direction is 41.0 deg counterclockwise. 
We estimated a rectangular error box for the transient source with the following corners:
(266.590, -1.392) deg = (17 46 21, -01 23 31) (J2000) 
(266.518, -1.475) deg = (17 46 04, -01 28 30) (J2000) 
(267.633, -2.210) deg = (17 50 31, -02 12 36) (J2000) 
(267.637, -2.281) deg = (17 50 32, -02 16 50) (J2000).
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).

The X-ray flux averaged over the scan was 1330 +- 75 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 01:42
and in the next transit at UT 04:48 with an upper limit of 20 mCrab for each.


GRB_name: GRB170830A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21764
SUBJECT: GRB 170830A: iTelescope optical observations
DATE:    17/08/30 09:48:50 GMT
FROM:    Denis Denisenko at SAI MSU  <d.v.denisenko@gmail.com>

D. Denisenko (Sternberg Astronomical Institute, Moscow State
University) reports:

MAXI/GSC error box of GRB 170830A (T. Yoneyama et al., GCN 21761) was
observed remotely by iTelescope.Net T32 instrument (0.43-m f/6.8
reflector + FLI Proline 16803 CCD) in Siding Spring, Australia, at
08:55-08:58 UT on 2017 Aug. 30 (5.7 hours after the trigger time). The
telescope was centered at R.A. = 17 48 20, Decl. = -01 50 00 with a
43'x43' field of view covering the entire rectangular error box by
MAXI/GSC. Observations were performed at the zenith distance of 31
degree, only 18 deg from the waxing Moon (phase 0.60).

Visual inspection of the combined image (3x60-sec unfiltered
exposures) against 1991-06-15 DSS Red plate shows no optical transient
to the 3-sigma upper limit of 18.5m (calibrated against USNO-B1.0 Red
magnitudes). In particular, there is no new object in the vicinity of
the unidentified ROSAT X-ray source 1RXS J174835.3-014843 which falls
inside the gamma-ray burst error box.


GRB_name: GRB080513A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21765
SUBJECT: LIGO/Virgo G298048: Discovery of X-ray emission from SSS17a in NGC4993
DATE:    17/08/30 12:07:12 GMT
FROM:    Eleonora Troja at GSFC/Swift  <nora.gsfc@gmail.com>

E. Troja (UMD/GSFC), L. Piro (INAF/IAPS), T. Sakamoto (AGU),
S. B. Cenko (NASA/GSFC), and A. Lien (UMBC/GSFC) report on behalf
of a larger collaboration:

We observed the field of SSS17a (Coulter et al., LVC GCN 21529) with
the Chandra X-ray Observatory under our approved guest observer program
(18500489; PI: E. Troja). Observations were carried out on 2017-08-26
(~9 days after the LVC trigger) for a total exposure of 50 ks.

We detect the extended X-ray source visible in previous observations
(Evans et al., LVC GCN 21612; Margutti et al., LVC GCN 21648) at a
comparable flux level. In addition, we detect an X-ray source at the
optical/IR transient position, approximately 10 arcsecond from the
centroid of the extended X-ray emission. The probability to find an
unrelated X-ray source within the small localization of the optical
transient is negligible (<1E-5).

Previous candidate kilonovae (e.g. GRB080513, Perley et al. 2009;
GRB130603B; Tanvir et al. 2013) were associated to transient X-ray
emission, although bright X-rays are not a basic prediction of this
model. In our case, the properties of the X-ray emission and the
overall spectral energy distribution appear different.
The most likely explanation seems that the observed X-rays arise from
the afterglow of GRB170817A (Connaughton et al., LVC GCN 21506;
Savchenko et al., LVC GCN 21507), thus confirming the spatial
association between the short GRB and SSS17a.

A newborn spinning-down magnetar could power a long-lived and nearly
constant X-ray emission (Zhang & Meszaros, 2001). However,
the observed timescale and X-ray luminosity would imply unrealistic
values of the initial spin period and magnetic field. The previous
lack of detection from Chandra (Margutti et al., LVC GCN 21648)
further disfavors this magnetar model. Other models (e.g. Metzger
& Piro, 2014) also do not match our observed luminosities and timescales.

For a standard on-axis afterglow, the extrapolation of the observed
flux would violate the upper limits reported by Evans et al.
(LVC GCN 21550), and Cenko et al. (LVC GCN 21572).

Our observations are instead consistent with the onset of an off-axis
afterglow from the GRB jet. This would explain the low luminosity of
the observed gamma-ray emission, and the lack of early afterglow
detections.

Further observations are planned.

We thank Belinda Wilkes and the entire CXC staff for rapidly scheduling
these observations.


GRB_name: GRB170826B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21767
SUBJECT: Konus-Wind observation of GRB 170826B
DATE:    17/08/30 15:05:24 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170826B (Fermi GBM observation: Poolakkil
et al., GCN 21717; Insight-HXMT detection: Li et al., GCN 21739;
IPN Triangulation: Hurley et al., GCN 21753)
triggered Konus-Wind at T0=70742.555 s UT (19:39:02.555).

The burst light curve shows a multipeaked structure
which starts at ~T0-3.9 s and has a total duration of ~23.6 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst
had a fluence of 5.70(-0.53,+0.53)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.728 s,
of 1.62(-0.29,+0.30)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+14.592 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.73(-0.14,+0.15),
the high energy photon index beta = -2.12(-0.14,+0.10),
the peak energy Ep = 261(-32,+46) keV
(chi2 = 87/83 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+6.400 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.54(-0.19,+0.20),
the high energy photon index beta = -2.05(-0.13,+0.09),
the peak energy Ep = 259(-36,+53) keV
(chi2 = 99/83 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170826_T70742/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170830A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21773
SUBJECT: GRB 170830A: Astrosat CZTI detection
DATE:    17/08/31 13:22:08 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Bhalerao (IITB), V. Sharma and D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of GRB 170830A (MAXI/GSC detection: Yoneyama T. et al., GCN Circ. 21761) in the 40-200 keV energy range. The light curve shows multiple peaks of emission with the strongest peak at 03:14:00 UT, ~89 s before the MAXI/GSC trigger. The measured peak count rate is 66.3 counts/sec above the background in combined data of four quadrants, with a total of 91.4 counts. The local mean background count rate was 395.1 counts/sec. Using cumulative rates, we measure a T90 of 57.6 secs.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170826A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21774
SUBJECT: Konus-Wind observation of GRB 170826A
DATE:    17/08/31 13:25:28 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration GRB 170826A
(Fermi GBM observation: Poolakkil et al., GCN Circ. 21715;
IPN Triangulation: Svinkin et al., GCN Circ. 21734)
triggered Konus-Wind at T0=31868.408 s UT (08:51:08.408).

The burst light curve shows a single pulse which starts
at ~T0-0.250 s and has a total duration of ~0.3 s.

As observed by Konus-Wind, the burst
had a fluence of 1.1(-0.2,+1.1)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.032 s,
of 1.1(-0.4,+1.2)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

Modeling the KW 3-channel time-integrated spectrum
(from T0-0.248 s to T0+0.040 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.15(-0.26,+0.46) and Ep = 682(-261,+3960) keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170826_T31868/

All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170827B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21775
SUBJECT: Konus-Wind observation of GRB 170827B
DATE:    17/08/31 14:13:20 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration GRB 170827B
(IPN Triangulation: Svinkin et al., GCN Circ. 21735)
triggered Konus-Wind at T0=70686.844 s UT (19:38:06.844).

The burst light curve shows a single pulse which starts
at ~T0-0.150 s and has a total duration of ~0.180 s.

As observed by Konus-Wind, the burst
had a fluence of 4.2(-0.8,+1.1)x10^-7 erg/cm2,
and a 16-ms peak flux, measured from T0+0.018 s,
of 3.8(-1.3,+1.5)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

Modeling the KW 3-channel time-integrated spectrum
(from T0-0.148 s to T0+0.032 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -0.21(-0.34,+0.56) and Ep = 345(-79,+121) keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170827_T70686/

All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170830A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21776
SUBJECT: GRB 170830A: Fermi GBM observation
DATE:    17/08/31 17:04:28 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

M. Stanbro (UAH), E. Bissaldi (Politecnico & INFN Bari)
and C. Meegan (UAH) report on behalf of the Fermi GBM Team:


"At 03:14:01.95 UT on 30 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170830A (trigger 525755646 / 170830135).
This trigger is likely associated with the transient source
reported by MAXI/GSC (Yoneyama et al., GCN 21761), which was also detected
by AstroSat (Bhalerao et al., GCN 21773).

The on-ground calculated location, using the GBM trigger
data, is

RA = 275.9, DEC = -4.0,

with an uncertainty of 2.6 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 100 degrees.

The GBM light curve shows two peaks
with a duration (T90) of about 110 s (50-300 keV).
The time-averaged spectrum from T0 to T0+92 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.54 +/- 0.07 and
the cutoff energy, parameterized as Epeak, is 180 +/- 40 keV.

The event fluence (10-1000 keV) in this time interval is
(4.20 +/- 0.11)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0 in the 10-1000 keV band
is 4.6 +/- 0.4 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170831A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21777
SUBJECT: GRB 170831A: Fermi GBM detection
DATE:    17/08/31 17:05:23 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 04:18:11.13 UT on 31 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170831A (trigger 525845896 / 170831179).

The on-ground calculated location, using the GBM trigger
data, is

RA = 158.7, DEC = +49.8

(J2000 degrees, equivalent to 10h 34m, 49d 48'), with an uncertainty
of 1.6 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32]).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 43 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 60 s (50-300 keV).
The time-averaged spectrum from T0-1.5 s to T0+55 s is
adequately fit by a Band function with Epeak = 90 +/- 5 keV,
alpha = -1.32 +/- 0.03, and beta = -2.52 +/- 0.12.

The event fluence (10-1000 keV) in this time interval is
(2.03 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+44 s in the 10-1000 keV band
is 23.8 +/- 0.4 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170902A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21788
SUBJECT: GRB 170902A: Swift detection of a burst or possible Galactic transient
DATE:    17/09/02 20:41:05 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

C. B. Markwardt (NASA/GSFC), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 20:00:36 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170902A (trigger=770431).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 233.895, -57.213, which is 
   RA(J2000)  =  15h 35m 35s
   Dec(J2000) = -57d 12' 44"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical for image triggers, there is nothing
significant in the real-time data. 

The XRT began observing the field at 20:07:20.4 UT, 404.1 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 233.8330, -57.2313 which is equivalent to:
   RA(J2000)  = +15h 35m 19.92s
   Dec(J2000) = -57d 13' 52.7"
with an uncertainty of 5.8 arcseconds (radius, 90% containment). This
location is 137 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to determine the
column density using X-ray spectroscopy. 

UVOT took a finding chart exposure of 128 seconds with the White filter
starting 413 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the large, but uncertain extinction expected. 

Because this is a long event (336 second image trigger) that is
close to the Galactic Plane (lat=-1.13 deg) there is a possibility
that this is a Galactic transient rather than a cosmic GRB. 
Determination of the nature of this object will require the full 
downlinked dataset and further observations. 

Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170902A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21790
SUBJECT: GRB 170902A: Enhanced Swift-XRT position
DATE:    17/09/03 03:46:40 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 3279 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 170902A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 233.83222, -57.23004 which is equivalent
to:

RA (J2000): 15h 35m 19.73s
Dec (J2000): -57d 13' 48.1"

with an uncertainty of 1.5 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170902A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21791
SUBJECT: Swift Trigger 770431 (GRB 170902A) is a not a GRB
DATE:    17/09/03 04:23:55 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

J. A. Kennea (PSU) and C. B. Markwardt (NASA/GSFC) report on behalf of the
Swift team:

Swift trigger 770431 (AKA GRB 170902A) is not a GRB, but a Galactic
Transient. The source was detected almost 4 hours after BAT triggered by
MAXI (Negoro et al. ATEL #10699) and the Swift X-ray light-curve measured
after the BAT trigger shows no evidence of fading (Kennea et al., ATEL
#10700). Therefore we conclude that this trigger is in fact from a new
Galactic Transient named MAXI J1535-571.


GRB_name: GRB170903A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21793
SUBJECT: GRB 170903A: Swift detection of a burst
DATE:    17/09/03 13:00:50 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

C. B. Markwardt (NASA/GSFC), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU),
K. L. Page (U Leicester), J. L. Racusin (NASA/GSFC) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 12:49:07 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170903A (trigger=770528).  Swift did not slew due to an observing
constraint.  The BAT on-board calculated location is 
RA, Dec 254.512, +34.983, which is 
   RA(J2000)  =  16h 58m 03s
   Dec(J2000) = +34d 59' 01"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a few peaks
with a total duration of about 30 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~4 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+49.5
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170903A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21794
SUBJECT: GRB 170903A: Swift-XRT observations
DATE:    17/09/03 14:34:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri
(INAF-OAB) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 170903A at 13:41:04.6 UT,
3117.5 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source with an enhanced position: RA, Dec
254.5260, 34.9796 which is equivalent to:
   RA(J2000)  = 16h 58m 06.23s
   Dec(J2000) = +34d 58' 46.6"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 43 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.74 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 6.3
(+3.39/-2.89) x 10^21 cm^-2 (90% confidence). 


GRB_name: GRB170903A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21795
SUBJECT: GRB 170903A: Nanshan optical upper limit
DATE:    17/09/03 15:01:49 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

H.X. Feng, D. Xu, Z.P. Zhu (NAOC), S.G. Ma, T.Z. Yang, J.H. Liu, P. 
Zong, H.B. Niu, J.Z. Liu,  A. Esamdin, L. Ma (all XAO), Y.D. Hu 
(IAA-CSIC), Y. Qing (Geneva Observatory) report:

We observed the field of GRB 170903A (Markwardt et al., GCN 21793) using 
the 1m telescope located at Nanshan, Xinjiang, China. We obtained 3x180s 
R-band frames, starting at 14:08:09 UT on 2017-09-03, i.e., 1.317 hr 
after the burst.

No optical source is detected at the XRT position (Campana et al., GCN 
21794) in the stacked image, down to a limiting magnitude of m(R)~21.3, 
calibrated with the nearby SDSS field.


GRB_name: GRB170903A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21796
SUBJECT: GRB 170903A: Swift-BAT refined analysis
DATE:    17/09/03 17:30:06 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
 
Using the data set from T-61 to T+242 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 170903A (trigger #770528)
(Markwardt, et al., GCN Circ. 21793).  The BAT ground-calculated position is
RA, Dec = 254.532, 34.985 deg, which is 
   RA(J2000)  =  16h 58m 07.7s 
   Dec(J2000) = +34d 59' 07.5" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 30%.
 
The mask-weighted light curve shows two slightly overlapping peaks starting
at ~T-5 sec, with a maximum at ~T+1 sec, and returning to baseline at ~T+70 sec.
T90 (15-350 keV) is 29.2 +- 4.4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-10.00 to T+25.70 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.94 +- 0.12.  The fluence in the 15-150 keV band is 2.4 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.58 sec in the 15-150 keV band
is 3.9 +- 0.5 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/770528/BA/


GRB_name: GRB170903A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21797
SUBJECT: GRB 170903A: Enhanced Swift-XRT position
DATE:    17/09/03 19:49:46 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1379 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 170903A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 254.52613, +34.97887 which is equivalent
to:

RA (J2000): 16h 58m 6.27s
Dec (J2000): +34d 58' 43.9"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170903A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21799
SUBJECT: GRB 170903A: Host galaxy redshift from OSIRIS/GTC 
DATE:    17/09/03 23:16:16 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), L. Izzo (HETH/IAA-CSIC)
C.C. Thoene (HETH/IAA-CSIC), D.A. Kann (HETH/IAA-CSIC), 
K.E. Heintz (DARK/NBI), N. Castro-Rodriguez (GRANTECAN, IAC, ULL), 
A. Marante (GRANTECAN) report on behalf of a larger collaboration:

We have observed the field of GRB 170903A (Markwardt et al., GCN 21793) 
with OSIRIS at the 10.4m GTC telescope. Observations started at 20:49 UT 
(8.0 hrs after the burst). Observations consisted of an acquisition image in 
i-band and 3x900s spectra with the R1000B grism, which covers the range 
between 3700 and 7880 AA.

The acquisition image shows a single source within the refined XRT error box
(Goad et al., GCN 21797), with an i-band magnitude (AB) of 23.17 +/- 0.15. 
The object appears unresolved at a seeing of 0.6â€. Spectroscopy of it shows a 
weak trace covering the complete range above 4000 AA and a single, very 
prominent emission feature. Due to the strength of this feature and the 
non-detection of any other features in the spectral range, we identify it as the 
unresolved [OII] 3727/3729 doublet at a redshift of 0.886, which we propose 
as the redshift of the host galaxy and hence of the GRB.


GRB_name: GRB170903A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21800
SUBJECT: GRB 170903A: Swift-XRT refined Analysis
DATE:    17/09/03 23:24:17 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B.
Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU),
S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester) and C.B. Markwardt report on behalf of the Swift-XRT team:

We have analysed 7.0 ks of XRT data for GRB 170903A (Markwardt et al.
GCN Circ. 21793), from 3.4 ks to 32.1 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Goad et al. (GCN Circ. 21797).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.41 (+/-0.08).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.22 (+0.19, -0.18). The
best-fitting absorption column is  5.6 (+1.1, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 1.7 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.7 x 10^-11 (7.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.6 (+1.1, -1.0) x 10^21 cm^-2
Galactic foreground: 1.7 x 10^20 cm^-2
Excess significance: 9.3 sigma
Photon index:      2.22 (+0.19, -0.18)

If the light curve continues to decay with a power-law decay index of
0.41, the count rate at T+24 hours will be 0.048 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x
10^-12 (3.5 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00770528.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170903A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21801
SUBJECT: GRB 170903A: MITSuME Okayama upper limits
DATE:    17/09/04 00:19:21 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of MITSuME and OISTER collaboration:

We observed the field of GRB 170903A (Markwardt et al., GCNC 21793)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2017-09-03 12:49:43 UT (~35 sec after
the burst). We did not find any new point source within the
enhanced XRT error circle (Goad et al., GCNC 21797) in all
the three bands.

Three sigma upper limits of the OT are listed below.
We used SDSS-DR8 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc     Ic
-----------------------------------------------------
0.03712    13:42:34    5280.0   >19.4  >19.5  >18.7
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB170903A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21805
SUBJECT: GRB 170903A: UAFO /ISON optical upper limit
DATE:    17/09/04 11:01:47 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI),  E. Chornaya (UAFO), A. Pozanenko (IKI), A. Volnova 
(IKI), A. Matkin (UAFO), I. Molotov (KIAM)  report on behalf of  larger 
GRB follow-up collaboration:

We observed the field of  Swift GRB 170903A  (Markwardt et al., GCN 
21793) with SANTEL-650 (0.65m)  telescope  of UAFO/ISON-Ussuriysk 
observatory. We obtained several unfiltered images starting on  Sep. 03 
(UT) 13:20:15.  Within enhanced XRT position (Goad et al., GCN 21797) we 
do not detect any source.  Preliminary photometry of a combined image is 
following

Date       UT start  t-T0     Filter  Exp.      OT   Err.  UL
                     (mid, days)       (s)

2017-09-03 13:20:15  0.04847  CR      120*30    n/d  n/d   20.4


Photometry is based on nearby SDSS DR9 stars
SDSS_DR9_id         R(Lupton)
J165744.06+345751.4 16.01
J165803.01+345725.1 16.56
J165808.53+350159.7 15.58
J165749.08+345655.1 16.66
J165805.88+345230.1 16.24


GRB_name: GRB170903A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21806
SUBJECT: GRB 170903A: Swift/UVOT Upper Limits
DATE:    17/09/04 11:02:08 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and C. B. Markwardt (NASA/GSFC) report on
behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170903A
3484 s after the BAT trigger (Markwardt et al., GCN Circ. 21793).
No optical afterglow consistent with the XRT position (Goad et al. GCN
Circ. 21797) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding
chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC          3484         3634          147         >20.7
white             3484         4865          344         >21.6
v                 3640         5275          393         >19.7
b                 4460         4660          197         >20.5
u                 4255         4455          197         >21.0
w1                4050         9664          362         >20.7
m2                3845         5482          393         >20.4
w2                4871         5071          197         >21.8

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.02 in the direction of the
burst (Schlegel et al. 1998).


GRB_name: GRB170827A
Detection_method: LCO
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21807
SUBJECT: GRB 170827A: LCO Observations
DATE:    17/09/04 11:43:05 GMT
FROM:    Antonino Cucchiara at UVI  <antonino.cucchiara@uvi.edu>

A. Cucchiara, D. Morris, J. Staff, and B. Gendre (U. Virgin
Islands) report on behalf of a larger collaboration:

"On August 27.71 UT  (T_0 +12.0h) we began observing the
center of the field of GRB 170827A (Marshall et al.
GCN 21718, D'Ai et al. GCN 21730) using the Las Cumbres
Observatory 1m telescope located in Sutherland Observatory.

We performed a series of 5x240s observations in SDSS r' and
iâ€™ bands for a total of 20 minutes on sky in each filter at
average airmass of 1.05.

In the full median stacked images we identified no optical
counterpart within the center of the Swift-XRT refined position
or at the ePESSTO NTT optical counterpart location (Evans et al.
GCN 21413, Lyman et al. GCN 21728) at the following
3-sigma limits:

r' > 20.6 mag
i' > 19.6 mag

These values are consistent with the limits and detections
reported by other observatories (D'Avanzo et al. GCN 21721,
Schady et al. GCN 21729, 21743).

These magnitudes are calibrated against nearby USNO-B1 sources,
converted in SDSS bands, and not corrected for Galactic extinction."


GRB_name: GRB170903A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21812
SUBJECT: GRB 170903A: Fermi GBM observation
DATE:    17/09/04 19:48:16 GMT
FROM:    Bill Paciesas at UAH  <bill.paciesas@nasa.gov>

F. Berlato (MPE) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 12:49:07.79 UT on 3 September 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170903A (trigger 526135752 / 170903534), which
was also detected by the Swift/BAT (Markwardt et al., GCN 21793).

The GBM on-ground localization is consistent with the Swift location.

The angle from the Fermi LAT boresight at the GBM trigger time is 93 degrees.

The GBM light curve shows two pulses with a duration (T90) of 
about 25 s (50-300 keV). The time-averaged spectrum from 
T0-1.5 s to T0+25.5 s is adequately fit by a Comptonized model, 
with index  -1.56 +/- 0.10 and Epeak 124 +/- 33 keV .
The event fluence (10-1000 keV) in the time interval is 
(4.34 +/- 0.54)E-06 erg/cm^2. The 1-sec peak photon flux (10-1000 keV) 
measured starting from T0-1.5 s is (5.80 +/- 0.36) ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170903A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21813
SUBJECT: GCN GRB 170903A
DATE:    17/09/04 20:48:43 GMT
FROM:    Francesco Berlato at MPE  <fberlato@mpe.mpg.de>

F Berlato (MPE) and C Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 12:49:07.79 UT on 3 September 2017, the Fermi Gamma-Ray Burst 
Monitor
triggered and located GRB 170903A (trigger 526135752 / 170903534), 
which
was also detected by the Swift/BAT (Markwardt et al., GCN 21793).

The Swift localization, consistent with the GBM one, is RA = 254.532 
deg,
DEC = 34.985 deg (J2000, equivalent to 16h 58m 7.7s, +34d 59' 7.5"),
with an uncertainty of 1.3 arcmin (radius, sys+stat, 90% containment).

The angle from the Fermi LAT boresight at the GBM trigger time is 93 
deg.

The GBM light curve shows two pulses with a duration (T90) of
about 25 s (50-300 keV). The time-averaged spectrum from
T0-1.5 s to T0+25.5 s is adequately fit by a Comptonized model,
with index  -1.56 +/- 0.10 and Epeak 124 +/- 33 keV .
The event fluence (10-1000 keV) in the time interval is
(4.34 +/- 0.54)E-06 erg/cm^2. The 1-sec peak photon flux (10-1000 keV)
measured starting from T0-1.5 s is (5.80 +/- 0.36) ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170904A
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21817
SUBJECT: GRB 170904A: Insight-HXMT detection
DATE:    17/09/05 12:57:02 GMT
FROM:    Zhengwei Li at IHEP  <lizw@ihep.ac.cn>

Z. W. Li, J. Y. Liao, C. K. Li, X. B. Li, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:


During the commissioning phase, at 2017-09-04T09:46:00.62 (T0),
Insight-HXMT detected GRB 170904A (trigger ID: HEB170904406)
in a routine search of the data, which was also observed by
INTEGRAL/SPI-ACS and Swift/BAT.


The Insight-HXMT light curve consists of multiple pulses
with a duration (T90) of 10.9 s measured from T0+0.1 s.
The 1-s peak rate, measured from T0+1.0 s, is 4655.1 cnts/sec.
The total counts from this burst is 43647.2 counts.


URL_LC: http://www.hxmt.org/images/GRB/HEB170904406_lc.jpg


All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.


The analysis results presented above are preliminary;
final results will be published elsewhere.


Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170901B
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21818
SUBJECT: GRB 170901B: Insight-HXMT detection
DATE:    17/09/05 12:59:54 GMT
FROM:    Zhengwei Li at IHEP  <lizw@ihep.ac.cn>

Z. W. Li, C. K. Li, J. Y. Liao, X. B. Li, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:


During the commissioning phase, at 2017-09-01T11:59:56.50 (T0),
Insight-HXMT detected GRB 170901B (trigger ID: HEB170901499)
in a routine search of the data, which was also observed by
INTEGRAL/SPI-ACS (trig #7906).


The Insight-HXMT light curve consists of multiple pulses
with a duration (T90) of 10.9 s measured from T0+0.3 s.
The 1-s peak rate, measured from T0+1.0 s, is 788.6 cnts/sec.
The total counts from this burst is 5722.0 counts.


URL_LC: http://www.hxmt.org/images/GRB/HEB170901499_lc.jpg


All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.




The analysis results presented above are preliminary;
final results will be published elsewhere.


Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170904A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21820
SUBJECT: IPN Triangulation of GRB 170904A (long/very bright)
DATE:    17/09/05 20:59:35 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team,

X. B. Li, Y. Huang, Z. W. Li, and S. L. Xiong,
on behalf of the Insight-HXMT team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration, very bright GRB 170904A (Li et al., GCN Circ. 21817)
was detected by Konus-Wind, INTEGRAL (SPI-ACS), Insight-HXMT (HE),
Mars-Odyssey (HEND), and Swift (BAT) at about 35161 s UT (09:46:01).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    35.374 (02h 21m 30s) -32.498 (-32d 29' 51")
  Corners:
    35.139 (02h 20m 33s) -34.082 (-34d 04' 56")
    35.438 (02h 21m 45s) -33.461 (-33d 27' 38")
    35.574 (02h 22m 18s) -30.892 (-30d 53' 32")
    35.302 (02h 21m 12s) -31.531 (-31d 31' 51")
  ---------------------------------------------
The error box area is 1934 sq. arcmin, and its maximum
dimension is 3.2 deg (the minimum one is 12.6 arcmin).
The Sun distance was 125 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170904_T35162/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170906A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21821
SUBJECT: GRB 170906A: Swift detection of a burst with an optical afterglow
DATE:    17/09/06 00:55:00 GMT
FROM:    David Burrows at PSU/Swift  <burrows@astro.psu.edu>

M. H. Siegel (PSU), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
C. Gronwall (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (PSU)
and A. Tohuvavohu (PSU) report on behalf of the Swift Team:

At 00:43:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170906A (trigger=770957).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 203.992, -47.125 which is 
   RA(J2000) = 13h 35m 58s
   Dec(J2000) = -47d 07' 28"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multiply-peaked
structure with a duration of about 120 sec.  The peak count rate
was ~16000 counts/sec (15-350 keV), at ~30 sec after the trigger. 

The XRT began observing the field at 00:44:18.9 UT, 67.3 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 203.9546, -47.1007 which is equivalent to:
   RA(J2000)  = +13h 35m 49.10s
   Dec(J2000) = -47d 06' 02.5"
with an uncertainty of 5.2 arcseconds (radius, 90% containment). This
location is 126 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to determine the
column density using X-ray spectroscopy. 

The initial flux in the 0.1 s image was 4.12e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 77 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 13:35:49.19 = 203.95497
  DEC(J2000) = -47:06:01.9  = -47.10054
with a 90%-confidence error radius of about 0.61 arc sec. This position is 1.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
16.59 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.14. 

Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170906B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21822
SUBJECT: GRB 170906B: Swift detection of a burst
DATE:    17/09/06 01:16:34 GMT
FROM:    David Burrows at PSU/Swift  <burrows@astro.psu.edu>

B. Sbarufatti (PSU), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
C. Gronwall (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), M. H. Siegel (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Swift Team:

At 00:55:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170906B (trigger=770958). Swift slewed immediately to the burst. 
The BAT on-board calculated location is
RA, Dec 232.221, -28.251 which is
   RA(J2000) = 15h 28m 53s
   Dec(J2000) = -28d 15' 03.6"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve is not immediately available
for an unknown reason. 

The XRT began observing the field at 00:57:04.2 UT, 78.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 232.2037, -28.2563
which is equivalent to:
   RA(J2000)  = 15h 28m 48.90s
   Dec(J2000) = -28d 15' 22.8"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 58 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.69 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 1.1
(+1.25/-0.71) x 10^22 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 80 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.42. 

Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170906B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21823
SUBJECT: GRB 170906B: Enhanced Swift-XRT position
DATE:    17/09/06 04:42:46 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 824 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 170906B, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 232.20430, -28.25599 which is equivalent
to:

RA (J2000): 15h 28m 49.03s
Dec (J2000): -28d 15' 21.6"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170906A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21824
SUBJECT: GRB 170906A: Enhanced Swift-XRT position
DATE:    17/09/06 06:43:24 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1313 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 170906A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 203.95523, -47.10089 which is equivalent
to:

RA (J2000): 13h 35m 49.26s
Dec (J2000): -47d 06' 03.2"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170906A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21825
SUBJECT: GRB 170906A: REM optical/NIR observations
DATE:    17/09/06 07:08:29 GMT
FROM:    Stefano Covino at Brera Astronomical Observatory  <stefano.covino@brera.inaf.it>

S. Covino, D. Fugazza (INAF / OAB) report on behalf of the REM team:

We observed the field of the GRB 170906A (Siegel et al., GCN 21821) with the 60-cm robotic 
telescope REM located at the La Silla Observatory (Chile).  The observations started at 00:44:23 UT, 
about 72 s after the burst, and were carried out simultaneously in the g, r, i, z and H bands.

A preliminary analysis shows that the optical counterpart reported by UVOT (Siegel et al., GCN 21821)
is well detected in all bands and between 2 and 3min after the burst it was:

r = 13.10 +- 0.10 (AB)
H = 12.00 +/- 0.05 (Vega)

Magnitudes are calibrated against the 2MASS catalog in the NIR and the APASS catalogue for the optical.


GRB_name: GRB170906C
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21826
SUBJECT: GRB 170906C: Swift detection of a burst
DATE:    17/09/06 07:37:56 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

M. H. Siegel (PSU), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester),
C. Gronwall (PSU), K. L. Page (U Leicester) and A. Tohuvavohu (PSU)
report on behalf of the Swift Team:

At 07:26:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170906C (trigger=770981).  Swift did not slew due to an
observing constraint.  The BAT on-board calculated location is 
RA, Dec 128.704, +70.782, which is 
   RA(J2000)  =  08h 34m 49s
   Dec(J2000) = +70d 46' 54"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows multiple overlapping peaks
with a total duration of about 30 sec.  The peak count rate
was ~4000 counts/sec (15-350 keV), at ~6 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+18.9
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170906A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21827
SUBJECT: GRB 170906A: Fermi-LAT detection
DATE:    17/09/06 08:12:32 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari), D. Kocevski (NASA/GSFC),
G. Vianello (Stanford University), M. Arimoto (Waseda University)
and J. Racusin (NASA/GSFC) report on behalf of the Fermi-LAT team:


At 00:43:11.66 UT on September, 06, 2017 Fermi-LAT detected high-energy emission
from GRB 170906A, which was also detected by Fermi-GBM (trigger 526351393 / 170906030)
and Swift (Siegel et al., GCN #21821).

The best LAT on-ground location is found to be

RA, Dec = 203.94, -47.12 (J2000)

with an error radius of 0.10 deg (90 % containment, statistical error only).
This is consistent with the enhanced Swift-XRT position (Beardmore et al., GCN #21824).
This was 75 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate that is
spatially and temporally correlated with the trigger with high significance.
The highest-energy photon is a 3.6 GeV event,
which is observed 200 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin@nasa.gov).


The Fermi-LAT is a pair conversion telescope designed to cover the energy band from
20 MeV to greater than 300 GeV. It is the product of an international collaboration
between NASA and DOE in the U.S. and many scientific institutions across
France, Italy, Japan and Sweden.


GRB_name: GRB170906C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21828
SUBJECT: GRB 170906C: Swift-XRT observations
DATE:    17/09/06 08:30:41 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows
(PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB) and G. Cusumano
(INAF-IASF PA) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 170906C at 07:47:49.6 UT,
1292.1 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 128.65022,
70.81211 which is equivalent to:
   RA(J2000)  = 08h 34m 36.05s
   Dec(J2000) = +70d 48' 43.6"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 125 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (3.30 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.1
(+0.39/-0.34) x 10^22 cm^-2 (90% confidence). 


GRB_name: GRB170829A
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21829
SUBJECT: GRB 170829A: Insight-HXMT detection
DATE:    17/09/06 08:41:38 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

X. Ma, C. K. Li, S. L. Xiong, X. B. Li, C. Z. Liu, X. F. Li,
Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-08-29T06:29:39.90 (T0),
Insight-HXMT/HE detected GRB 170829A (trigger ID: HEB170829270)
in a routine search of the data, which was also observed by
INTEGRAL/SPI-ACS.

The Insight-HXMT light curve consists of multiple pulses
with a duration (T90) of 3.1 s measured from T0.
The 0.5-s peak rate, measured from T0+1.0 s, is 1660.5 cnts/sec.
The total counts from this burst is 3924.2 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170829270_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170906A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21830
SUBJECT: GRB 170906A: MASTER-OAFA (Argentina) early automatic  OT detection
DATE:    17/09/06 09:01:51 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Kuvshinov, 
P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko, I.Gorbunov, A.V.Krylov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias


K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

V. Yurkov, A. Gabovich, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk


D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory

MASTER-OAFA  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Argentina was pointed to the  Swift  GRB170906A (Siegel rt al. 
GCN21821)  44 sec after trigger time at 2017-09-06 00:43:56 UT with 10 
sec exposition.
Robot  found 1  optical transient within SWIFT error-box (ra=13:35:49.19 
dec=-47:06:01.9  r=0.61(90%)) at

RA, DEC = 13h 35m 49.3s , -47d  6m 02.7s

We see OT brightenning from unfiltered mag  15.6 up to 14.4 at 2017-09-06 
00:50:54  UT (midle time).

The 5-sigma upper limit on the single images has been about 16.8mag

This OT was also detected by UVOT (Siegel et al GCN 21821) and REM
(Covino et al. GCN 21825).

The observations made on zenit distance = 64 degrees, galaxy latitude b = 
15 degree.
The moon (100 % bright part) is 35 degrees above the horizon. The distance 
between  moon and  object is 113
The sun  altitude  is -31.7 degree.
The object can be observed till 2017-09-06 04:04:24.

The message may be cited.


GRB_name: GRB170906C
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21831
SUBJECT: GRB 170906C: Enhanced Swift-XRT position
DATE:    17/09/06 10:23:57 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1795 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 170906C, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 128.65367, +70.81162 which is equivalent
to:

RA (J2000): 08h 34m 36.88s
Dec (J2000): +70d 48' 41.8"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170906C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21832
SUBJECT: GRB 170906C: Swift-BAT refined analysis
DATE:    17/09/06 14:56:29 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. H. Siegel (PSU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170906C (trigger #770981)
(Siegel, et al., GCN Circ. 21826).  The BAT ground-calculated position is
RA, Dec = 128.659, 70.805 deg, which is
   RA(J2000)  =  08h 34m 38.1s
   Dec(J2000) = +70d 48' 16.7"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.

The mask-weighted light curve shows multiple overlapping peaks starting at
~T-40 sec, peaking at ~T+7 sec, and returning to baseline at ~T+100 sec.
T90 (15-350 keV) is 48.4 +- 4.7 sec (estimated error including systematics).

The time-averaged spectrum from T-35.21 to T+39.22 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.30 +- 0.22,
and Epeak of 104.8 +- 43.0 keV (chi squared 47.9 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 8.8 +- 0.3 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+6.18 sec in the 15-150 keV band is
7.2 +- 0.5 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.67 +- 0.05 (chi squared 56.9 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/770981/BA/


GRB_name: GRB170906C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21834
SUBJECT: GRB 170906C: Swift-XRT refined Analysis
DATE:    17/09/06 15:32:12 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), A.
Tohuvavohu (PSU), S. J. LaPorte (PSU), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri
(INAF-OAB) and M.H. Siegel report on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 170906C (Siegel et al. GCN
Circ. 21826), from 1.3 ks to 20.2 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Evans et al. (GCN Circ. 21831).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.65 (+0.07, -0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.69 (+0.21, -0.20). The
best-fitting absorption column is  9.4 (+1.4, -1.3) x 10^21 cm^-2, in
excess of the Galactic value of 3.3 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.4 x 10^-11 (1.2 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      9.4 (+1.4, -1.3) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^20 cm^-2
Excess significance: 11.3 sigma
Photon index:      2.69 (+0.21, -0.20)

If the light curve continues to decay with a power-law decay index of
0.65, the count rate at T+24 hours will be 0.027 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.1 x
10^-13 (3.2 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00770981.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170906C
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21835
SUBJECT: GRB 170906C: Swift/UVOT Upper Limits
DATE:    17/09/06 16:50:16 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170906C
1296 s after the BAT trigger (Siegel et al., GCN Circ. 21826).
No optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 21828)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC          1296         1446          147         >21.6
white             1296         2585          284         >21.4
v                 1578         2635          136         >19.4
b                 1504         2913          333         >19.9
u                 1479         2708          156         >20.6
w1                1454         2684          156         >19.9
m2                2467         2487           19         >17.8
w2                2591         2611           19         >19.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170906A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21836
SUBJECT: GRB 170906A: Swift-XRT refined Analysis
DATE:    17/09/06 19:39:09 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A.
Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester),
P.A. Evans (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB) and M.H. Siegel report on behalf of the Swift-XRT team:

We have analysed 6.4 ks of XRT data for GRB 170906A (Siegel et al. GCN
Circ. 21821), from 71 s to 62.4 ks after the  BAT trigger. The data
comprise 683 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 21824).

The late-time light curve (from T0+10.2 ks) can be modelled with a
power-law decay with a decay index of alpha=2.08 (+0.27, -0.25).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.64 (+/-0.03). The
best-fitting absorption column is  2.60 (+0.16, -0.15) x 10^21 cm^-2,
in excess of the Galactic value of 1.4 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.23 (+0.24, -0.23)
and a best-fitting absorption column of 4.7 (+1.3, -1.1) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.5 x 10^-11 (6.6 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.7 (+1.3, -1.1) x 10^21 cm^-2
Galactic foreground: 1.4 x 10^21 cm^-2
Excess significance: 4.9 sigma
Photon index:      2.23 (+0.24, -0.23)

If the light curve continues to decay with a power-law decay index of
2.08, the count rate at T+24 hours will be 2.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x
10^-13 (1.9 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00770957.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170906C
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21837
SUBJECT: GRB 170906C: COATLI Observations
DATE:    17/09/06 19:47:21 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Carlos
RomÃ¡n-ZÃºÃ±iga (UNAM), and William H. Lee (UNAM) report:

We observed the field of the GRB 170906C (Siegel et al., GCN Circ.
21826) with the COATLI 50-cm telescope and interim CCD imager (Watson et
al. 2016, Proc. SPIE, 9908, 50) at the Observatorio AstronÃ³mico Nacional
on the Sierra de San Pedro MÃ¡rtir from 2017-09-06 08:17 to 12:11
obtaining a total of 2.93 hours of observation in the clear w filter.

We do not detect a source within the enhanced XRT error region reported
by Evans et al. (GCN Circ. 21831). Calibrating with respect to the
USNO-B1 catalog, we estimate a 3-sigma upper limit of:

w > 21.7

This magnitude is in the AB system and is not corrected for Galactic
extinction in the direction of the GRB.

We thank the COATLI technical team (Fernando Ãngeles, Oscar Chapa,
Salvador Cuevas, Alejandro Farah, Jorge Fuentes, RosalÃ­a Langarica,
Fernando QuirÃ³s, and Carlos Tejada) and the staff of the Observatorio
AstronÃ³mico Nacional.


GRB_name: GRB170906A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21838
SUBJECT: GRB 170906A: Swift-BAT refined analysis
DATE:    17/09/06 20:53:57 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. H. Siegel (PSU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+603 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170906A (trigger #770957)
(Siegel, et al., GCN Circ. 21821).  The BAT ground-calculated position is
RA, Dec = 203.949, -47.088 deg, which is 
   RA(J2000)  =  13h 35m 47.7s 
   Dec(J2000) = -47d 05' 18.3" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.
 
The mask-weighted light curve shows multiple peaks starting at ~T-40 sec,
with a max peak at ~T+30, and returning to baseline at ~T+170 sec.
T90 (15-350 keV) is 88.1 +- 1.5 sec (estimated error including systematics).
 
The time-averaged spectrum from T-44.9 to T+121.5 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.21 +- 0.10, 
and Epeak of 205.4 +- 71.9 keV (chi squared 36.4 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 3.2 +- 0.0 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T+29.82 sec in the 15-150 keV band is
10.9 +- 0.4 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.45 +- 0.02 (chi squared 52.7 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/770957/BA/


GRB_name: GRB170906A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21839
SUBJECT: GRB 170906A: Fermi GBM detection
DATE:    17/09/06 21:32:38 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

R. Hamburg (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 00:43:08.15 UT on 06 September 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170906A (trigger 526351393 / 170906030),
which was also detected by Swift (Siegel et al. 2017, GCN  21821).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 75
degrees.

The GBM light curve shows a multi-peaked structure
with a duration (T90) of about 79 s (50-300 keV).
The time-averaged spectrum from T0-2.6 s to T0+107.0 is
best fit by a Band function with Epeak = 288 +/- 12 keV,
alpha = -1.02 +/- 0.02, and beta = -2.09 +/- 0.04.

The event fluence (10-1000 keV) in this time interval is
(1.17 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+33.4 s in the 10-1000 keV band
is 21.7 +/- 0.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170906B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21840
SUBJECT: GRB 170906B: Fermi GBM detection
DATE:    17/09/06 21:33:57 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

R. Hamburg (UAH) and and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 00:55:40.85 UT on 06 September 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170906B (trigger 526352145 / 170906039).
which was also detected by Swift (Sbarufatti et al. 2017, GCN 21822).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 53
degrees.

The GBM light curve shows a two-peaked emission
with a duration (T90) of about 12 s (50-300 keV).
The time-averaged spectrum from T0-0.0 s to T0+12.8 s is
well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.11 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 59 +/- 4 keV.

The event fluence (10-1000 keV) in this time interval is
(2.7 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+5.1 s in the 10-1000 keV band
is 10.3 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170906B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21841
SUBJECT: GRB 170906B: Swift-BAT refined analysis
DATE:    17/09/07 01:21:12 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), B. Sbarufatti (PSU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from the recent telemetry downlink,
we report further analysis of BAT GRB 170906B (trigger #770958)
(Sbarufatti et al., GCN Circ. 21822).

Because this burst occurred only 755 s after the trigger time of GRB 170906A
(trigger #770957), data collection was interrupted, and as such we do not have
event-by-event data during the burst. Thus most of the usual BAT data products
that we usually report in the "refined analysis circular" are not available.

The BAT raw light curve shows roughly two overlapping pulses that start
at ~T-11 s and ends at ~T+7 s. The two peaks occur at ~T-5 s and ~T0,
respectively.

The results of the BAT analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/770958/BA/


GRB_name: GRB170906C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21843
SUBJECT: GRB 170906C: optical observations
DATE:    17/09/07 09:58:45 GMT
FROM:    Luca Izzo at IAA-CSIC  <Luca.Izzo@ICRA.it>

L. Izzo, A. de Ugarte Postigo, D.A. Kann (IAA-CSIC/HETH) report on behalf of a larger collaboration:

We observed the field of GRB 170906C (Siegel et al., GCN 21826) with the T24 (Plane Wave CDK 0.61m) of the iTelescope.Net (http://www.itelescope.net) located at Auberry, CA. A set of 3 images of 300 s each were taken in the I filter, starting at 10:30:39 UT, ~ 2.9 hours after the GRB trigger.

We do not detect any source inside the XRT refined error region (Evans et al., GCN 21831) and estimate a 3-sigma upper limit of I > 19.0


GRB_name: GRB170906B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21845
SUBJECT: GRB 170906B: Swift-XRT refined Analysis
DATE:    17/09/07 13:44:59 GMT
FROM:    Boris Sbarufatti at INAF-OAB/IASFPA  <boris.sbarufatti@brera.inaf.it>

B. Sbarufatti (PSU) reports on behalf of the Swift-XRT team:

We have analysed 831 s of XRT data for GRB 170906B (Sbarufatti et al.
GCN Circ. 21822), from 63 s to 924 s after the BAT trigger. The data
comprise 9 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Osborne et al. (GCN Circ.
21823).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.63 (+0.13, -0.14).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.80 (+0.30, -0.27). The
best-fitting absorption column is  7.5 (+2.8, -2.2) x 10^21 cm^-2, in
excess of the Galactic value of 1.7 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 5.0 x 10^-11 (7.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      7.5 (+2.8, -2.2) x 10^21 cm^-2
Galactic foreground: 1.7 x 10^21 cm^-2
Excess significance: 4.3 sigma
Photon index:      1.80 (+0.30, -0.27)

If the light curve continues to decay with a power-law decay index of
0.63, the count rate at T+24 hours will be 0.033 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-12 (2.6 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00770958.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170906B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21846
SUBJECT: GRB 170906B: Swift/UVOT Upper Limits
DATE:    17/09/07 15:06:30 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170906B
81 s after the BAT trigger (Sbarufatti et al., GCN Circ. 21822).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 21823)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            81          231          147         >20.2
u_FC               293          543          246         >19.3
white               81          930          243         >20.6
v                  623          815           39         >17.5
b                  548          741           39         >18.7
u                  293          716          265         >19.3
w1                 672          865           39         >18.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.42 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170906A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21847
SUBJECT: GRB 170906A: Swift/UVOT Detection
DATE:    17/09/07 18:30:36 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170906A
77 s after the BAT trigger (Siegel et al., GCN Circ. 21821).
A source consistent with the XRT position (Siegel et al. GCN Circ. 21821)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
   RA  (J2000) =  13:35:49.20 = 203.95501 (deg.)
   Dec (J2000) = -47:06:02.1  = -47.10057 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are listed
below.  The afterglow appears to have brightened during the early observations and
faded by later orbits, confirming the analysis of Lipunov et al. (GCN Circ. 21830).


Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white (fc)         77           227          147         16.41 +/- 0.03
white              570          590           19         15.47 +/- 0.04
white              744          764           19         15.65 +/- 0.05
v                  620          639           19         14.65 +/- 0.07
v                11125        23192          901        >19.82
b                  545          565           20         15.59 +/- 0.06
b                12629        12744          112        >19.63
u                  290          539          246         15.47 +/- 0.03
u                  694          714           19         15.47 +/- 0.08
u                17786        18086          295        >19.82
uvm2             15973        16873          885        >20.09
uvw1               669          689           19         17.00 +/- 0.24
uvw1             16880        17780          885        >20.23
uvw2               595          615           19        >17.0
uvw2             10219        22561         1771        >20.61

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170904A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21852
SUBJECT: Konus-Wind observation of GRB 170904A
DATE:    17/09/08 15:12:36 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, hard-spectrum, bright GRB 170904A
(IPN Triangulation: Hurley et al., GCN 21820)
triggered Konus-Wind at T0=35162.28 s UT (09:46:02.280).

The burst light curve shows multiple emission pulses
in the interval from ~T0-56 s ~T0+30 s.
The emission is seen up to ~19 MeV.
Weak count rate increases are seen in the same S1 KW detector
at ~T0-560 s and ~T0-350 s, however their attribution to this
GRB is unclear.

As observed by Konus-Wind, the burst
had a fluence of 1.73(-0.09,+0.09)x10^-4 erg/cm2,
and a 64-ms peak energy flux, measured from T0+11.728 s,
of 1.90(-0.32,+0.32)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+22.016 s)
is best fit in the 20 keV - 19 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.69(-0.05,+0.06),
the high energy photon index beta = -2.17(-0.10,+0.08),
the peak energy Ep = 466(-36,+40) keV,
chi2 = 115/97 dof.

The spectrum near the peak count rate
(measured from T0+9.984 to T0+11.776 s)
is best fit in the 20 keV - 19 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.73(-0.11,+0.13),
the high energy photon index beta = -2.19(-0.24,+0.15),
the peak energy Ep = 441(-72,+87) keV,
chi2 = 53/67 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170904_T35162/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170830B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21855
SUBJECT: GRB 170830B CALET Gamma-Ray Burst Monitor detection
DATE:    17/09/09 12:53:50 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto, Y. Kawakubo,
M. Moriyama, Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa,
S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR),
M. L. Cherry (LSU), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170830B (Fermi-GBM trigger #525772316;
Konus-Wind trigger time on 07:51:50.164 UT; INTEGRAL-SPI/ACS trigger
#7903,0) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 07:51:52.372
on 30 August 2017.  The burst signal was seen by the all CGBM instruments.
Because of a problem in one of the ground alert processing script,
the GCN notice was not distributed automatically for this event.

The light curve of the SGM shows a single peak.  The emission starts at
T0 sec, peaks at T+2 sec and ends at T+3.5 sec.  The T90 duration measured
by the SGM data is 3.3 +- 0.5 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1188114098/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170906A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21856
SUBJECT: GRB 170906A: AstroSat CZTI(Veto) detection
DATE:    17/09/11 14:29:14 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IIT-B), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:

The bright GRB 170906A was detected using the CsI veto detectors on Astrosat CZTI (Bhalerao et al., arXiv:1608.03408),  which was also detected by Swift (Siegel M.H. et al., GCN Circ. 21821) and Fermi GBM (Hamburg R. et al, GCN Circ. 21839).

The source was clearly detected in the 125-250 keV energy range. The light curve shows a multiple peak structure. The peak count rate in the CsI detectors was 2262 counts/sec above the background (four quadrants summed together), with a total of 49316 counts. The local mean background count rate was 1606.7 counts/sec. Using cumulative rates, we measure a T90 of 70.5 secs.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb . CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170906C
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21857
SUBJECT: Konus-Wind observation of GRB 170906C
DATE:    17/09/11 15:53:01 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170906C (Swift-BAT trigger #770981:
Siegel et al., GCN 21826; Lien et al., GCN 21832)
triggered Konus-Wind at T0=26780.985 s UT (07:26:20.985).

The burst light curve shows a single pulse
started at ~T0-40.8 s with a total duration of ~65.8 s.
The emission is seen up to ~4 MeV.

As observed by Konus-Wind, the burst
had a fluence of  1.60(-0.19,+0.28)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+0.354 s,
of 2.77(-0.73,+0.74)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.06(-0.18,+0.19),
and Ep = 154(-19,+26) keV (chi2 = 64/72 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.56 (chi2 = 64/71 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170906_T26780/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170911A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21858
SUBJECT: GRB 170911A: MAXI/GSC detection
DATE:    17/09/11 15:54:51 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

Y. Takao (RIKEN), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA),
T. Mihara, M. Sugizaki, S. Nakahira, W. Iwakiri, M. Shidatsu, M. Matsuoka (RIKEN), 
N. Kawai, S. Sugita, T. Yoshii, Y. Tachibana, S. Harita, Y. Muraki, K. Morita (Tokyo Tech), 
A. Yoshida, T. Sakamoto, M. Serino, Y. Kawakubo, Y. Kitaoka, T. Hashimoto (AGU), 
H. Tsunemi, T. Yoneyama (Osaka U.),
M. Nakajima, T. Kawase, A. Sakamaki (Nihon U.),
Y. Ueda, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), 
Y. Tsuboi, Y. Nakamura, R. Sasaki, H. Kawai (Chuo U.), 
M. Yamauchi, C. Hanyu, K, Hidaka (Miyazaki U.), 
T. Kawamuro (NAOJ), and K. Yamaoka (Nagoya U.)


The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source 
at 06:24:21 UT on 2017 September 11.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (72.100 deg, 30.914 deg) = (04 48 23, +30 54 50) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.38 deg and 0.32 deg, respectively. 
The roll angle of long axis from the north direction is 8.0 deg counterclockwise. 
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 119 +- 24 mCrab
(4.0-10.0keV, 1 sigma error).
Without the constant flux assumption, we also obtained a rectangular error box 
for the transient source with the following corners:
(R.A., Dec) = (70.630, 31.515) deg = (04 42 31, +31 30 55) (J2000)
(R.A., Dec) = (70.464, 30.944) deg = (04 41 51, +30 56 38) (J2000)
(R.A., Dec) = (73.457, 30.459) deg = (04 53 49, +30 27 31) (J2000)
(R.A., Dec) = (73.640, 31.026) deg = (04 54 33, +31 01 34) (J2000)
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).

There was no significant excess flux in the previous transit at 04:51
and in the next transit at 07:56 with an upper limit of 20 mCrab for each.

Fermi is likely to detected this burst (Trigger number: 526803867).


GRB_name: GRB170906A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21859
SUBJECT: Konus-Wind observation of GRB 170906A
DATE:    17/09/11 16:11:07 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170906A (Swift-BAT trigger #770957:
Siegel et al., GCN 21821; Cummings et al., GCN 21838;
Fermi-LAT detection: Bissaldi et al., GCN 21827;
Fermi GBM detection: Hamburg & Meegan, GCN 21839;
AstroSat CZTI(Veto) detection: Sharma et al., GCN 21856)
triggered Konus-Wind at T0=2607.999 s UT (00:43:27.999).

The burst light curve shows a double-peaked structure
started at ~T0-23 s with a total duration of ~91 s,
followed by a weaker emission seen up to ~T0+135 s.
The KW data above 1.5 MeV are largely contaminated
by high solar particle background.

As observed by Konus-Wind, the burst
had a fluence of 1.19(-0.21,+0.22)x10^-4 erg/cm2,
and a 64-ms peak energy flux, measured from T0+11.184 s,
of 9.25(-2.67,+2.97)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+68.608 s)
is best fit in the 20 keV - 1.5 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.91(-0.10,+0.12),
the high energy photon index beta = -2.41(-0.94,+0.28),
the peak energy Ep = 274(-37,+43) keV,
chi2 = 86/59 dof.

The spectrum near the peak count rate
(measured from T0+6.400 to T0+16.384 s)
is best fit in the 20 keV - 1.5 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.60(-0.12,+0.15),
the high energy photon index beta = -2.36(-0.75,+0.31),
the peak energy Ep = 360(-54,+58) keV,
chi2 = 64/59 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170906_T02607/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170912A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21861
SUBJECT: GRB 170912A: Swift detection of a burst
DATE:    17/09/12 01:45:00 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Tohuvavohu (PSU), D. N. Burrows (PSU), C. Gronwall (PSU),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), B. Sbarufatti (PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 01:34:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170912A (trigger=772006).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 167.372, -54.360 which is 
   RA(J2000) = 11h 09m 29s
   Dec(J2000) = -54d 21' 34"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peak
structure with a duration of about 20 sec.  The peak count rate
was ~1200 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 01:36:15.6 UT, 118.7 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 167.37341, -54.32690 which
is equivalent to:
   RA(J2000)  = 11h 09m 29.62s
   Dec(J2000) = -54d 19' 36.8"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 119 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 3.14
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 122 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.46. 

Burst Advocate for this burst is A. Tohuvavohu (aaronb AT swift.psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170912A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21862
SUBJECT: GRB 170912A: Prompt enhanced Swift-XRT position
DATE:    17/09/12 02:14:56 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 170912A, we find an
enhanced XRT position of the afterglow: RA, Dec: 167.3734, -54.3262
which is equivalent to:
   RA (J2000)  = 11 09 29.61
   Dec (J2000) = -54 19 34.4
with an uncertainty of 2.2 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/772006.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170912A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21863
SUBJECT: GRB 170912A: Enhanced Swift-XRT position
DATE:    17/09/12 05:24:57 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 426 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 170912A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 167.37343, -54.32638 which is equivalent
to:

RA (J2000): 11h 09m 29.62s
Dec (J2000): -54d 19' 35.0"

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170912B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21864
SUBJECT: GRB 170912B: Swift detection of a burst
DATE:    17/09/12 06:47:58 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. J. LaPorte (PSU), J. A. Kennea (PSU), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of
the Swift Team:

At 06:33:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170912B (trigger=772052).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 215.466, -62.030 which is 
   RA(J2000) = 14h 21m 52s
   Dec(J2000) = -62d 01' 47"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 20 sec.  The peak count rate
was ~9500 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 06:34:36.9 UT, 50.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 215.45921, -61.99674 which
is equivalent to:
   RA(J2000)  = 14h 21m 50.21s
   Dec(J2000) = -61d 59' 48.3"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 120 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density. 

The initial flux in the 2.5 s image was 4.76e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 58 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. Because of the density of catalogued stars, further
analysis is required to report an upper limit for any afterglow in the
sub-image. The 8'x8' region for the list of sources generated on-board covers
100% of the XRT error circle. Because of the density of catalogued stars,
further analysis is required to report an upper limit for any afterglow in the
region. No correction has been made for the large, but uncertain extinction
expected. 

Burst Advocate for this burst is S. J. LaPorte (extragsam AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170912B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21868
SUBJECT: GRB 170912B: Enhanced Swift-XRT position
DATE:    17/09/12 10:59:09 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1328 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 170912B, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 215.45854, -61.99709 which is equivalent
to:

RA (J2000): 14h 21m 50.05s
Dec (J2000): -61d 59' 49.5"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170911A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21869
SUBJECT: GRB 170911A: Fermi GBM observation
DATE:    17/09/12 11:49:28 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE), R. Hamburg (UAH), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 06:24:22.79 UT on 11 September 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170911A (trigger 526803867 / 170911267)
which was also detected by the MAXI GSC
(Takao et al. 2017, GCN 21858)
The GBM on-ground location is consistent with the MAXI position.

The angle from the Fermi LAT boresight at the GBM trigger time is 43 degrees.

The GBM light curve shows a single peak
with a duration (T90) of about 20 s (50-300 keV).
The time-averaged spectrum from T0-3.072 s to T0+4.096 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.2 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 260 +/- 120 keV


The event fluence (10-1000 keV) in this time interval is
(9.5 +/- 1.7)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.79 s in the 10-1000 keV band
is 1.96 +/- 0.17 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170912B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21872
SUBJECT: GRB 170912B: Fermi GBM observations
DATE:    17/09/12 16:05:35 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P Veres (UAH), A von Kienlin (MPE) and C Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 06:33:46.91 UT on 12 September 2017, the Fermi Gamma-Ray Burst
Monitor triggered and located GRB 170912B (trigger 526890831 /
170912273) which was also detected by the Swift satellite (LaPorte et
al., GCN 21864). The GBM on-ground location is consistent with the
Swift position.

The angle from the Fermi LAT boresight at the GBM trigger
time is 39 degrees.

The GBM light curve shows multiple overlapping peaks
with a duration (T90) of about 13.3 s (50-300 keV).
The time-averaged spectrum from T0-1.7 s to T0+13.7 s is
best fit by a Band function with Epeak = 45.2 +/- 6.0 keV,
alpha = -0.88 +/- 0.23, and beta = -2.13 +/- 0.06.

The event fluence (10-1000 keV) in this time interval is
(4.5 +/- 0.2)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.1 s in the 10-1000 keV band
is 8.7 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170912B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21873
SUBJECT: GRB 170912B: Swift-XRT refined Analysis
DATE:    17/09/12 16:08:31 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson
(U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V.
D'Elia (ASDC) and S.J. LaPorte report on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 170912B (LaPorte et al. GCN
Circ. 21864), from 45 s to 23.8 ks after the  BAT trigger. The data
comprise 15 s in Windowed Timing (WT) mode (the first 3 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Osborne et
al. (GCN Circ. 21868).

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.69 (+/-0.09), followed by a break at T+3083 s to an
alpha of 1.9 (+0.4, -0.3).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.7 (+/-0.3). The
best-fitting absorption column is  4.1 (+0.9, -0.8) x 10^22 cm^-2, in
excess of the Galactic value of 1.7 x 10^22 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 8.9 x 10^-11 (1.7 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.1 (+0.9, -0.8) x 10^22 cm^-2
Galactic foreground: 1.7 x 10^22 cm^-2
Excess significance: 4.8 sigma
Photon index:      1.7 (+/-0.3)

If the light curve continues to decay with a power-law decay index of
1.9, the count rate at T+24 hours will be 4.4 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.9 x
10^-14 (7.6 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00772052.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170912A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21874
SUBJECT: GRB 170912A: Swift/UVOT Upper-Limits
DATE:    17/09/12 17:07:43 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 170912A: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and Tohuvavohu (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170912A
122 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 21861).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 21863)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           122          272          147         >20.9
u_FC               335          585          246         >19.4
white              122         1362          373         >21.6
v                  666         1412           97         >18.8
b                  591         1338           78         >19.6
u                  335         1313          304         >19.2
w1                 715         1461           78         >18.7
m2                 690         1436           78         >20.0
w2                 641         1387           97         >19.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.46 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170912A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21876
SUBJECT: GRB 170912A: Swift-XRT refined Analysis
DATE:    17/09/12 21:32:08 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), P.A. Evans (U.
Leicester), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), P.
D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), D.N.
Burrows (PSU) and A. Tohuvavohu report on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 170912A (Tohuvavohu et al.
GCN Circ. 21861), from 104 s to 62.2 ks after the  BAT trigger. The
data comprise 17 s in Windowed Timing (WT) mode (the first 8 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by Goad
et al. (GCN Circ. 21862).

The light curve can be modelled with a power-law decay with a decay
index of alpha=4.8 (+nan, -nan).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.85 (+0.54, -0.22). The
best-fitting absorption column is  consistent with the Galactic value
of 3.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.9 x 10^-11 (5.4 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.1 (+/-2.3) x 10^21 cm^-2
Galactic foreground: 3.1 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.85 (+0.54, -0.22)

If the light curve continues to decay with a power-law decay index of
4.8, the count rate at T+24 hours will be 1.4 x 10^-13 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.4 x
10^-24 (7.4 x 10^-24) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00772006.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170912A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21877
SUBJECT: GRB 170912A: Swift-BAT refined analysis
DATE:    17/09/12 21:42:52 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
A. Tohuvavohu (PSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170912A (trigger #772006)
(Tohuvavohu et al., GCN Circ. 21861).  The BAT ground-calculated position is
RA, Dec = 167.386, -54.343 deg which is
  RA(J2000)  =  11h 09m 32.6s
  Dec(J2000) = -54d 20' 35.4"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 34%.

The mask-weighted light curve shows a single-peaked structure that starts
at ~T0, peaks at ~T+3, and ends at ~T+25 s. T90 (15-350 keV) is
21.9 +- 5.6 sec (estimated error including systematics).

The time-averaged spectrum from T-0.42 to T+25.64 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.04 +- 0.21.  The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.38 sec in the 15-150 keV band
is 2.0 +- 0.4 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/772006/BA/


GRB_name: GRB170912B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21879
SUBJECT: GRB 170912B: Swift-BAT refined analysis
DATE:    17/09/13 01:42:01 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+480 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170912B (trigger #772052)
(LaPorte et al., GCN Circ. 21864).  The BAT ground-calculated position is
RA, Dec = 215.464, -61.997 deg which is
  RA(J2000)  =  14h 21m 51.3s
  Dec(J2000) = -61d 59' 50.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows several overlapping pulses that starts
at ~ T0 and ends at ~ T+40 s. T90 (15-350 keV) is 19.6 +- 6.2 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.93 to T+38.75 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.88 +- 0.07.  The fluence in the 15-150 keV band is 2.4 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.07 sec in the 15-150 keV band
is 5.7 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/772052/BA/


GRB_name: GRB170912B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21881
SUBJECT: GRB 170912B: Swift/UVOT Upper Limits
DATE:    17/09/14 02:44:20 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

S. J. LaPorte (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170912B
60 s after the BAT trigger (LaPorte et al., GCN Circ. 21864).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 21868)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter        T_start(s)  T_stop(s)  Exp(s)    Mag

white_FC      57          207        147       >20.26  
white         58          1024       332       >20.72
v             600         1074       58        >18.08    
b             525         718        38        >18.76 
u             269         1144       299       >19.67
uvw1          649         1124       58        >18.24  
uvm2          624         1099       58        >18.12   
uvw2          575         1050       58        >18.39  


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 5.05 in the direction of the burst
(Schlegel et al. 1998).

[GCN OPS NOTE(14sep17): Per author's request, the typo in the Subject-line
was changed from "170712B" to "170912B".


GRB_name: GRB170906A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21884
SUBJECT: GRB 170906A CALET Gamma-Ray Burst Monitor detection
DATE:    17/09/15 04:28:50 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

A. V. Penacchioni, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa,
S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR),
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170906A (Siegel et al., GCN Circ. 21821; Hamburg et al.,
GCN Circ. 21839; Tsvetkova et al., GCN Circ. 21859) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 00:43:05.59 on 6 September 2017.  The burst signal was
seen by the all CGBM instruments.

The light curve of the SGM shows a complex structure.  The emission starts at T0 sec
and the brightest pulse peaks at T+35 sec.  The entire emission ends at T+100 sec.
The T90 duration measured by the SGM data is 78.4 +- 1.9 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1188693801/

The CALET data used in this analysis are provided by the Waseda CALET Operation
Center located at the Waseda University.


GRB_name: GRB170912C
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21892
SUBJECT: GRB 170912C: Insight-HXMT detection
DATE:    17/09/17 03:10:31 GMT
FROM:    Yue Huang at IHEP  <huangyue@ihep.ac.cn>

Y. Huang, C. K. Li, S. L. Xiong, X. B. Li, C. Z. Liu, X. F. Li,
Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:
During the commissioning phase, at 2017-09-12T23:38:12.600 (T0),
Insight-HXMT/HE detected GRB 170912C (trigger ID: HEB170912984)
in a routine search of the data, which was also observed by
Fermi/GBM(trig #526952297).
The Insight-HXMT light curve consists of a single pulse
with a duration (T90) of 0.067 s measured from T0+0.010.
The 10-ms peak rate, measured from T0+0.041 s, is 8298.5 cnts/sec.
The total counts from this burst is 354 counts.
URL_LC: http://www.hxmt.org/images/GRB/HEB170912984_lc.jpg
All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.
The analysis results presented above are preliminary;
final results will be published elsewhere.
Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome.


GRB_name: GRB170921A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21901
SUBJECT: GRB 170921A: Swift detection of a burst
DATE:    17/09/21 14:44:31 GMT
FROM:    Boris Sbarufatti at PSU  <bxs60@psu.edu>

A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC), P. A. Evans (U Leicester),
J.D. Gropp (PSU), J. A. Kennea (PSU), H. A. Krimm (NSF/USRA),
S. J. LaPorte (PSU), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), B. Sbarufatti (PSU) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 14:28:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170921A (trigger=773509).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 26.849, +30.874 which is 
   RA(J2000) = 01h 47m 24s
   Dec(J2000) = +30d 52' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 20 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 14:30:25.8 UT, 97.3 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 26.8484,
30.9069 which is equivalent to:
   RA(J2000)  = 01h 47m 23.63s
   Dec(J2000) = +30d 54' 24.8"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 118 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (5.49 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.4
(+0.67/-0.55) x 10^22 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 100 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.05. 

Burst Advocate for this burst is A. D'Ai (antonino.dai AT ifc.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170921B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21902
SUBJECT: GRB 170921B: Fermi GBM detection
DATE:    17/09/21 16:19:13 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari) report on behalf of the Fermi GBM Team:


"At 04:02:11.51 UT on 21 September 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170921B (trigger 527659336 / 170921168).

The on-ground calculated location, using the GBM trigger data, is

RA = 134.38, DEC = +46.46

(J2000 degrees, equivalent to 08 h 57m, 46d 27'), with an uncertainty
of 1.6 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32]).

The angle from the Fermi LAT boresight at the GBM trigger time is 101 degrees.

The GBM light curve consists of a bright FRED-like peak
with a duration (T90) of about 34 s (50-300 keV).
The time-averaged spectrum from T0 to T0+30 s is
adequately fit by a Band function with Epeak = 100 +/- 10 keV,
alpha = -1.2 +/- 0.1, and beta = -2.3 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(5.4 +/- 0.1)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.1 s in the 10-1000 keV band
is 38.7 +/- 0.6 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170921A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21903
SUBJECT: GRB 170921A: TAROT Calern observatory optical observations
DATE:    17/09/21 19:35:55 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:

We imaged the field of GRB 170921A detected by SWIFT
(trigger 773509) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 3.86h after the GRB trigger.
The elevation of the field increased from
12 degrees above horizon and weather conditions
were good.

We co-added a series of exposures.
No OT is detected with a limiting magnitude of:

t0+3.86h to t0+4.23h : Rlim = 19.5

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB170921A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21904
SUBJECT: GRB 170921A: Swift-XRT refined Analysis
DATE:    17/09/21 22:29:22 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

B. Sbarufatti (INAF-OAB/PSU), S.L. Gibson (U. Leicester), J.P. Osborne
(U. Leicester), K.L. Page (U. Leicester), V. D'Elia (ASDC), A. Melandri
(INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU) and A. D'Ai report
on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 170921A (D'Ai et al. GCN
Circ. 21901), from 82 s to 16.5 ks after the  BAT trigger. The data
comprise 8 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The best
available XRT position (using the promptly downlinked event data, the
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1
catalogue) is RA, Dec = 26.8487, 30.9067 which is equivalent to:

RA (J2000): 01 47 23.70
Dec(J2000): +30 54 24.3

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

The light curve can be modelled with an initial power-law decay with an
index of alpha=3.3 (+0.5, -0.4), followed by a break at T+238 s to an
alpha of 0.85 (+0.10, -0.09).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.7 (+0.4, -0.3). The
best-fitting absorption column is  1.00 (+0.27, -0.23) x 10^22 cm^-2,
in excess of the Galactic value of 5.5 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.5 x 10^-11 (1.2 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.00 (+0.27, -0.23) x 10^22 cm^-2
Galactic foreground: 5.5 x 10^20 cm^-2
Excess significance: 6.7 sigma
Photon index:      2.7 (+0.4, -0.3)

If the light curve continues to decay with a power-law decay index of
0.85, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.3 x
10^-14 (2.5 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00773509.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170921A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21905
SUBJECT: GRB 170921A: MITSuME Okayama upper limits
DATE:    17/09/21 22:40:42 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Subaru, NAOJ), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech) report on behalf of MITSuME collaboration:

We observed the field of GRB 170921A (D'Ai et al., GCNC 21901)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2017-09-21 14:39:14 UT (~10 min after
the burst). We did not find any new point source within the XRT
error circle (D'Ai et al., GCNC 21901) in all the three bands.

Three sigma upper limits of the OT are listed below.
We used SDSS-DR8 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc     Ic
-----------------------------------------------------
0.04269    15:30:16    5760.0   >20.1  >19.8  >18.8
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB170921A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21906
SUBJECT: GRB 170921A: Enhanced Swift-XRT position
DATE:    17/09/21 23:19:36 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2671 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 170921A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 26.84906, +30.90673 which is equivalent
to:

RA (J2000): 01h 47m 23.77s
Dec (J2000): +30d 54' 24.2"

with an uncertainty of 1.5 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170921A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21907
SUBJECT: GRB 170921A: Nanshan optical upper limit
DATE:    17/09/22 00:33:24 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

H.X. Feng (NAOC), Y.D. Hu (IAA-CSIC), D. Xu, Z.P. Zhu (NAOC), X. Zhang, T.Z. Yang, J.Z. Liu, A. Esamdin, L. Ma (XAO), Y. Qin (Geneva Obs.) report:  We observed the field of long GRB 170921A (D'Ai et al., GCN 21901) using the 1m telescope located at Nanshan, Xinjiang, China. We obtained 3*180s R-band frames, starting at 15:52:35.04 UT on 2017-09-21 (i.e., 1.39 hr after the BATtrigger).  No optical source is detected at the XRT position (Beardmore et al., GCN 21906) in the stacked image, down to a limiting magnitude of m(R)~20.3, calibrated with the USNO-B1 catalog. 


GRB_name: GRB170921A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21909
SUBJECT: GRB 170921A: NOT optical observations
DATE:    17/09/22 07:23:28 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DARK/NBI), K. E. Heintz (Univ. Iceland and DARK/NBI), N. R. 
Tanvir (Univ. Leicester), D. A. Kann (IAA/CSIC), T. Pursimo (NOT), and 
S. Dyrbye (NOT) report on behalf of a larger collaboration:

We observed the field of GRB 170921A (D'Ai et al., GCN 21901) with the 
Nordic Optical Telescope equipped with the AlFOSC imager. Observations 
were carried out with the SDSS r' and z' filters, for a total exposure 
of 900 and 1800 s, respectively.

We did not detect any new object inside or in the proximity of the 
enhanced X-ray error circle (Beardmore et al., GCN 21906). At mean 
epochs 2017 Sep 21.941 and Sep 21.958 UT (8.1 and 8.5 hr after the GRB), 
we report 3-sigma limiting magnitudes r' > 24.3 and z' > 23.3, 
respectively (both AB, calibrated against the Pan-STARRS catalog).

Our non-detections are consistent with the reports by TAROT (Klotz et 
al., GCN 21903), MITSuME (Kuroda et al., GCN 21905), and Nanshan (Feng 
et al., GCN 21907).


GRB_name: GRB170921A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21910
SUBJECT: GRB 170921A: LCO 2m telescope observations
DATE:    17/09/22 12:07:33 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), 
A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara, D. Morris, 
and B. Gendre (U. Virgin Islands) on behalf of a large collaboration report:

We began observing Swift GRB 170921A (D'Ai et al. GCN 21901) on 
September 21, from 14:52 to 15:05 UT (from 24 to 37 minutes since the 
GRB trigger time) with the LCO 2-m telescope in Hawaii in the SDSS R and 
I filters. Within the enhanced Swift-XRT circle (Beardmore et al. GCN 
21906) we do not detect any optical counterpart down to the following 
limits, in agreement with previous reports (Klotz et al. GCN 21903; 
Kuroda et al. GCN 21905; Feng et al. GCN 21907; Malesani et al. GCN 21909):

Mid Time Exposure Filter Magnitude (AB)
(min) (s)
-------------------------------------------------------
26.8 5x60 SDSS-R > 20.7
34.0 3x60 SDSS-I > 19.8
-------------------------------------------------------

as calibrated against nearby SDSS objects.


GRB_name: GRB170918A
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21911
SUBJECT: GRB 170918A: Insight-HXMT detection
DATE:    17/09/22 13:44:54 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

S. L. Xiong, X. B. Li, C. K. Li, C. Z. Liu, X. F. Li,
Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-09-18T21:43:35.40 (T0),
Insight-HXMT/HE detected GRB 170918A (trigger ID: HEB170918905)
in a routine search of the data. No other observation for this GRB has
been reported yet.

The Insight-HXMT light curve mainly consists of a single pulse
with a duration (T90) of 0.98 s measured from T0+0.068 s.
The 100-ms peak rate, measured from T0+0.056 s, is 2278.3 cnts/sec.
The total counts from this burst is 1217.5 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170918905_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170921A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21912
SUBJECT: GRB 170921A: Swift-BAT refined analysis
DATE:    17/09/22 14:27:15 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), A. D'Ai (INAF-IASFPA)
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170921A (trigger #773509)
(D'Ai et al., GCN Circ. 21901).  The BAT ground-calculated position is
RA, Dec = 26.840, 30.880 deg which is
  RA(J2000)  =  01h 47m 21.6s
  Dec(J2000) = +30d 52' 47.1"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 86%.

The mask-weighted light curve shows a single-peaked structure that starts at
~T-22 s, peaks at ~T+3 s, and ends at ~T+13 s. T90 (15-350 keV) is
28.9 +- 6.0 sec (estimated error including systematics).

The time-averaged spectrum from T-21.82 to T+13.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.76 +- 0.17.  The fluence in the 15-150 keV band is 6.7 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+2.74 sec in the 15-150 keV band
is 0.8 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/773509/BA/


GRB_name: GRB170921A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21913
SUBJECT: GRB 170921A: Swift/UVOT Upper Limits
DATE:    17/09/22 14:56:56 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 170921A: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:
(Beardmore et al. GCN Circ. 21906)
The Swift/UVOT began settled observations of the field of GRB 170921A
101 s after the BAT trigger (D'Ai et al., GCN Circ. 21901).
No optical afterglow consistent with the XRT position

is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           101          251          147         >20.7
u_FC               259          509          246         >20.4
white              101         6816          766         >21.4
v                  590         7186          451         >19.9
b                  516         6611          471         >20.6
u                  259        12926         1346         >21.1
w1                 639        12273         1171         >20.6
m2                1412        11366         1102         >21.0
w2                 566        16512          687         >21.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170921A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21915
SUBJECT: GRB 170921A: RATIR Optical Afterglow Detection and NIR Observations
DATE:    17/09/22 23:22:09 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), JesÃºs
GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 170921A (D'Ai, et al., GCN 21901) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/09 22.18 to 2017/09 22.51 UTC (13.82 to
21.76 hours after the BAT trigger), obtaining a total of 5.29 hours
exposure in the r and i bands and 2.22 hours exposure in the Z, Y, J, and H
bands.

For a source within the Swift-XRT error circle (Beardmore, et al., GCN
21906), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the
following weak detections and upper limits (3-sigma):

  r = 24.45 +/- 0.34
  i = 24.38 +/- 0.34
  Z > 23.05
  Y > 22.83
  J > 22.47
  H > 22.19

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170921B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21918
SUBJECT: IPN Triangulation of GRB 170921B
DATE:    17/09/23 14:57:18 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration GRB 170921B (Bissaldi, GCN 21902) was detected
by Fermi (GBM trigger 527659336), Konus-Wind, INTEGRAL (SPI-ACS),
Mars-Odyssey (HEND), and Swift (BAT) at about 14531 s UT (04:02:11).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   132.375 (08h 49m 30s) +57.057 (+57d 03' 24")
  Corners:
   112.726 (07h 30m 54s) +39.192 (+39d 11' 30")
   113.512 (07h 34m 03s) +41.297 (+41d 17' 50")
   162.356 (10h 49m 25s) +62.282 (+62d 16' 56")
   160.088 (10h 40m 21s) +62.030 (+62d 01' 49")
  ---------------------------------------------
The error box area is 8.7 sq. deg, and its maximum
dimension is 37.5 deg (the minimum one is 14.4 arcmin).
The Sun distance was 63 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170921_T14528/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170921C
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21919
SUBJECT: GRB 170921C: Insight-HXMT detection
DATE:    17/09/23 17:59:37 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

Y. F. Zhang, S. L. Xiong, J. Y. Liao, C. K. Li, X. B. Li, C. Z. Liu,
X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-09-21T00:43:37.00 (T0),
Insight-HXMT/HE detected GRB 170921C (trigger ID: HEB170921030)
with a significance of 12 sigma in a routine search of the data,
which is also detected by Fermi/GBM subthreshold trigger
(trig time: 2017-09-21T00:43:37.18).

The Insight-HXMT light curve mainly consists of a single pulse
with a duration (T90) of 1.2 s measured from T0-0.27 s.
The 500-ms peak rate, measured from T0+0.06 s, is 1220.3 cnts/sec.
The total counts from this burst is 1247.3 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170921030_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .

[GCN OPS NOTE(26sep17):  The name was changed from "21A" to "21C".]


GRB_name: GRB170906A
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21921
SUBJECT: GRB 170906A: Insight-HXMT detection
DATE:    17/09/24 03:22:42 GMT
FROM:    Yifei Zhang at IHEP  <zhangyf@ihep.ac.cn>

Y. F. Zhang, S. L. Xiong, J. Y. Liao, C. K. Li, X. F. Lu, X. B. Li,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, J. L. Zhao, A. M. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-09-06T00:43:06.00 (T0),
Insight-HXMT/HE detected GRB 170906A (trigger ID: HEB170906029)
in a routine search of the data,which is also detected by CALET
(Penacchioni et al., GCN 21884), Fermi/GBM (Hamburg et al., GCN 21839)
and Swift/BAT (Siegel et al., GCN 21821).

The Insight-HXMT light curve mainly consists of multi-pulses
with a duration (T90) of 64.6 s measured from T0+2.3 s. 
The 1-second peak rate, measured from T0+35.3 s, is 1870.6 cnts/sec.
The total counts from this burst is 26305.3 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170906029_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The time-averaged spectrum from T0-5 s to T0+70 s is
adequately fit by a Power Law model with spectral index = -2.70 +/- 0.06.
The energy fluence is (5.94 +/- 0.20)E-04 erg/cm^2 in 200 - 5000 keV
in this time interval.


The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .


GRB_name: GRB170921B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21922
SUBJECT: GRB 170921B: AstroSat CZTI detection
DATE:    17/09/24 09:52:46 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), D. Bhattacharya (IUCAA), V. Bhalerao (IITB), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of short GRB 170921B (Fermi GBM detection: Bissaldi E. et al, GCN Circ. 21902) in the 40-200 keV energy range. The light curve shows a bright FRED-like emission with peak at 04:02:11.51 UT, coinciding with Fermi/GBM trigger. The measured peak count rate is 473.5 counts/s above the background in combined data of four quadrants, with a total 4475 counts. The local mean background count rate was 332 counts/s. Using cumulative rates, we measure a T90 of 30.5 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170921C
Detection_method: Insight-HXMT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21925
SUBJECT: Correction to GCN Circular 21919: GRB 170921C: Insight-HXMT detection
DATE:    17/09/25 06:25:32 GMT
FROM:    Yifei Zhang at IHEP  <zhangyf@ihep.ac.cn>

Y. F. Zhang and the Insight-HXMT collaboration



We just find that the GRB name (GRB 170921A) used in our pervious
GCN circular (Zhang et al. GCN 21919) is wrong. The correct GRB name
is GRB 170921C since GRB 170921A and GRB 170921B were already named
for the GRBs detected respectively by Swift/BAT on 14:28:48 UT 
(D'Ai et al. GCN 21901) and Fermi/GBM on 04:02:11.51 UT
(Bissaldi et al. GCN 21902). Apologies for any confusion caused.


GRB_name: GRB170921B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21926
SUBJECT: Konus-Wind observation of GRB 170921B
DATE:    17/09/25 16:20:31 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170921B
(Fermi GBM detection: Bissaldi, GCN Circ. 21902;
IPN Triangulation: Hurley et al., GCN Circ. 21918)
triggered Konus-Wind at T0=14528.886 s UT (04:02:08.886).

The burst light curve shows a single pulse which
starts at ~T0-0.2 s and has a total duration of ~25 s.
This pulse passes into a weaker decaying tail,
which can be traced out to ~T0+164 s.
The emission is seen up to ~4 MeV.

As observed by Konus-Wind, the burst
had a fluence of 5.44(-0.22,+0.22)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.704 s,
of 6.75(-1.20,+1.21)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+22.528 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.42(-0.05,+0.05)
and Ep = 138(-6,+7) keV (chi2 = 76/72 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.3
(chi2 = 76/71 dof)

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+2.048 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model
with  alpha = -0.33(-0.13,+0.14)
and Ep = 318(-22,+25) keV (chi2 = 52/67 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.7
(chi2 = 52/66 dof)

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170921_T14528/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170728B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21932
SUBJECT: GRB 170728B: Kottamia R-band observation
DATE:    17/09/27 06:13:52 GMT
FROM:    Yasser Hendy at NRIAG  <y_hendy_yasser@yahoo.com>

TITLE:   GCN CIRCULAR
NUMBER:  
SUBJECT: GRB 170728B: Kottamia R-band observation
DATE:    17/09/27 6:09 GMT
FROM:    Yasser Hendy at NRIAG  <y_hendy_yasser@yahoo.com>
 
G. B. Ali, Y.H.M. Hendy, A. Takey, N. Essam, and A. Essam 
National Research institute of Astronomy and Geophysics, NRIAG, Egypt

report on behalf of the Kottamia collaboration:

We observed the field of the short GRB 170728B: trigger=765130 
(Cenko S. B. et al., GCN Circ. 21371) with the 1.88m telescope 
of the KAO (Kottamia Astronomical Observatory), Egypt. 
The observation was performed in the Rc-band at the Newtonian
camera (F4.8) and started at 2017-07-29 T18:11:19 UT 
(~ 19.13 hours (0.8 day) after the burst). 

We obtained four images in the Rc-band each one with 600s exposure
time.  We clearly detected the optical afterglow (D'Avanzo et al., GCN Circ.
21372/21373; Heintz et al., GCN Circ. 21374; Guidorzi et al., GCN Circ. 21375; 
Izzo et al., GCN Circ. 21381; Kitaoka et al., GCN Circ. 21387; Watson et al., 
GCN Circ. 21389; Dintinjana et al., GCN Circ. 21394; Volnova et al., GCN Circ. 21419). 

We estimate a magnitude Rc 20.625 +/- 0.133, calibrated against nearby 
USNO-B1.0 stars:

  USNO-B1.0    R2 
1601-0108297  13.35
1600-0109901  13.61
1600-0109913  14.08
1601-0108263  14.58
1601-0108285  14.59
1601-0108292  14.71
1601-0108254  15.04
1600-0109911  15.42
1600-0109861  15.52
1601-0108199  15.66
1600-0109905  15.92
1600-0109885  15.97

-Yasser Hendy, on behalf of tthe Kottamia collaboration
 GRB followup team.



======================================================================
Dr. Yasser Hassan Mohamed  Mohamed  Hendy 
National Research Institute of Astronomy & Geophysics (NRIAG), 
Astronomy Department, 11421 Helwan, Cairo, Egypt. 
Phone: +202 25560645      Fax: +202 25548020      Mobile: +20 1007580213    +20 1145385285     
Email: y_hendy_yasser@yahoo.com  yasserhendy@nriag.sci.eg   yasserhendy@mail.ru 
Homepage:    NRIAG       ResearchGate     GoogleScholar      Facebook      vk
======================================================================


GRB_name: GRB170428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21942
SUBJECT: 3.6m Devasthal Optical Telescope observations of GRB 170428A
DATE:    17/09/28 13:19:00 GMT
FROM:    Shashi Bhushan Pandey at ARIES, INDIA  <shashi@aries.res.in>

S. B. Pandey (ARIES Nainital), Brajesh Kumar, G. C. Anupama (IIA Bangaluru) 
and Kuntal Misra (ARIES Nainital) on behalf of a larger GRB collaboration 


Short-duration GRB 170428A (Swift trigger =750298, Beardmore et al. GCN 21042) 
was observed by the 3.6m Devasthal Optical Telescope (DOT) recently commissioned 
by ARIES Nainital. The observations were carried out as a part of early science 
run and characterizations. Observations were carried out just before twilight 
using the 4Kx4K CCD optical imager, the first light instrument. Several R-band 
exposures of 300-sec each were acquired in seeing conditions of around 1.1 arcsec 
starting around UT 22:45:57 i.e. 13.5 hours after the burst. 

In the stacked R-band frame of 3*300-sec, the candidate optical afterglow (Xu et al. 
GCN 21048; Bolmer et al. GCN 21050) was clearly seen embedded within the host galaxy. 
The photometry at the afterglow position measures a magnitude of 22.7+-0.2 mag 
(calibrated with respect to nearby USNO stars). However, in the present data-set, 
contamination with the probable host galaxy can not be ruled out in the estimated magnitude. 

This is the first GRB afterglow observations with the 3.6m DOT and the full team of 
staff members associated with the project are thankfully acknowledged to get this telescope 
commissioned. We expect to contribute towards observations of time critical events in 
near future assuming longitudinal advantage of Indian sub-continent using this facility. 

The message may be cited. 


GRB_name: GRB171001A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21946
SUBJECT: GRB 171001A: Swift detection of a burst
DATE:    17/10/01 18:38:25 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Y. Lien (GSFC/UMBC), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU),
J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), D. M. Palmer (LANL),
M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the
Swift Team:

At 18:25:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171001A (trigger=775553).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 22.088, -11.893 which is 
   RA(J2000) = 01h 28m 21s
   Dec(J2000) = -11d 53' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~900 counts/sec (15-350 keV), at ~20 sec after the trigger. 

The XRT began observing the field at 18:28:53.9 UT, 193.7 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 22.0774, -11.8940 which
is equivalent to:
   RA(J2000)  = 01h 28m 18.59s
   Dec(J2000) = -11d 53' 38.5"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 37 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (3.56 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.9
(+3.76/-3.10) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 197 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.03. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170822A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21947
SUBJECT: GRB 170822A: 15 GHz upper limits from AMI
DATE:    17/10/01 20:07:24 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170822A (Melandri et al., GCN 21640) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 30 days 
post-burst. Our observations at 15 GHz on 2017 Aug 22.42, Aug 25.34, Aug 
26.34, Aug 30.37, Sep 03.28 and Sep 20.26 (UT) do not reveal any radio 
source at the XRT location (Beardmore et al., GCN 21643), with 3sigma 
upper limits of 165 uJy, 132 uJy, 138 uJy, 210 uJy, 210 uJy and 138 uJy 
respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170823A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21948
SUBJECT: GRB 170823A: 15 GHz upper limits from AMI
DATE:    17/10/01 20:09:17 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170823A (Troja et al., GCN 21666) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2017 Aug 24.41, Aug 25.61 and 
Aug 26.58 (UT) do not reveal any radio source at the BAT location 
(Stamatikos et al., GCN 21678). While we are dynamic range limited due 
to a bright radio source in the vicinity of the GRB location, we are 
able to place 3sigma upper limits of 1.0 mJy, 1.1 mJy, and 0.8 mJy at 
the respective epochs.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170906C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21949
SUBJECT: GRB 170906C: 15 GHz upper limits from AMI
DATE:    17/10/01 20:11:13 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170906C (Siegel et al., GCN 21826) as part of the 4pisky program. Our 
observation at 15 GHz on 2017 Sep 06.55 (UT) does not reveal any radio 
source at the XRT location (Evans et al., GCN 21831), with a 3sigma 
upper limit of 156 uJy. Further follow up observations have not been 
possible due to telescope maintenance.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170903A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21950
SUBJECT: GRB 170903A: 15 GHz upper limits from AMI
DATE:    17/10/01 20:12:06 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170903A (Markwardt et al., GCN 21793) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2017 Sep 03.57, Sep 04.79, Sep 
06.82, Sep 12.66 (UT) do not reveal any radio source at the XRT location 
(Goad et al., GCN 21797), with 3sigma upper limits of 225 uJy, 120 uJy, 
126 uJy, 99 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170921A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21951
SUBJECT: GRB 170921A: 15 GHz upper limits from AMI
DATE:    17/10/01 20:13:58 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170921A (D'Ai et al., GCN 21901) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2017 Sep 21.89, Sep 27.04 and 
Sep 28.97 (UT) do not reveal any radio source at the XRT location 
(Beardmore et al., GCN 21906), with 3sigma upper limits of 186 uJy, 117 
uJy and 159 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB171001A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21952
SUBJECT: GRB 171001A: Enhanced Swift-XRT position
DATE:    17/10/01 20:57:34 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1293 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 171001A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 22.07740, -11.89417 which is equivalent
to:

RA (J2000): 01h 28m 18.58s
Dec (J2000): -11d 53' 39.0"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB171001A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21953
SUBJECT: GRB171001A: D50 optical limit
DATE:    17/10/01 22:50:08 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

Martin Jelinek, Jan Strobl and Rene Hudec (ASU CAS Ondrejov)

We observed the field of the Swift GRB171001A (trigger #775553, Lien et al.
GCNC 21946) with the 0.5m telescope of Ondrejov observatory, the obseration
started at 21:17UT, i.e. about 2.9h after trigger and lasted for 30 miutes,
when the field became observable. On a series of unfiltered exposures we do
not detect any new object within or in the vicinity of the XRT errorbox
(Evans et al., GCNC 21952) down to the USNO-B/R2 calibrated limit  of
R>20.0.


GRB_name: GRB171001A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21954
SUBJECT: GRB 171001A: IRSF Observation
DATE:    17/10/02 01:07:51 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata@u.phys.nagoya-u.ac.jp>

R. Itoh (Tokyo Tech), K. L. Murata (Tokyo Tech), K. Morihana (Nagoya U.)
and T. Nagayama (Kagoshima U)

We observed the field of GRB 171001A (Lien et al., GCNCircular #21946) with
the near-infrared (J, H, Ks) simultaneous imaging camera SIRIUS attached to
1.4 m telescope IRSF (InfraRed Survey Facility) in Sutherland observatory,
South Africa.

The observations started on 2017-10-01 19:16:51 UT. We detected the
afterglow within the enhanced XRT error circle (Evans et al., GCN Circular
#21952) in J band. The measured magnitudes (Vega magnitude system) were
listed as below.

T0+[min]    MID-UT      T-EXP[sec]        J                 H
Ks
-------------------------------------------------------------------------------------------------
~48         19: 31              1270            17.0+-1.1      >16.3
>16.0
-------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time

Given magnitudes were calibrated against 2MASS point sources in this field.

This observation was carried out by IRSF and OISTER collaboration.


GRB_name: GRB171001A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21955
SUBJECT: GRB 171001A: Swift/UVOT Detection
DATE:    17/10/02 09:52:10 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 171001A
198 s after the BAT trigger (Lien et al., GCN Circ. 21946). The source
was found in the IR J band by Itoh et al. (GCN. Circ. # 21954). We find
a source consistent with the XRT position (Evans et al. GCN Circ. 21952) in
the initial UVOT exposures.

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white              198         1359          373         21.23 +/- 0.30
v                  686         1409           58        >18.2
b                  612         1503           93        >19.8
u                  356          780          265        >20.3
w1                 736         1458           58        >20.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB171001A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21956
SUBJECT: GRB 171001A: Swift-XRT refined Analysis
DATE:    17/10/02 11:19:25 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J.
LaPorte (PSU) and A.Y. Lien report on behalf of the Swift-XRT team:

We have analysed 6.0 ks of XRT data for GRB 171001A (Lien et al. GCN
Circ. 21946), from 176 s to 52.2 ks after the  BAT trigger. The data
comprise 11 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Evans et al. (GCN Circ.
21952).

The light curve can be modelled with an initial rise, with a power-law
index of alpha=-0.13 (+0.19, -0.21), followed by a break at T+1318 s 
to an alpha of 1.88 (+0.24, -0.18).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.09 (+0.21, -0.19). The
best-fitting absorption column is  6.2 (+4.6, -2.7) x 10^20 cm^-2,
consistent with the Galactic value of 3.6 x 10^20 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 3.1 x 10^-11 (3.7 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.2 (+4.6, -2.7) x 10^20 cm^-2
Galactic foreground: 3.6 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.09 (+0.21, -0.19)

If the light curve continues to decay with a power-law decay index of
1.88, the count rate at T+24 hours will be 2.1 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.6 x
10^-15 (7.8 x 10^-15) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00775553.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB171001A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21957
SUBJECT: GRB 171001A: Nanshan-0.36m optical afterglow detections
DATE:    17/10/02 12:21:09 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

H.J. Tan (CCU), H.X. Feng, D. Xu, Z.P. Zhu (NAOC), Y.D. Hu (IAA-CSIC), 
Y. Qin (Geneva Obs.), X. Gao (Urumqi No.1 Senior High School) report:

We observed the field of GRB 171001A (Lien et al., GCN 21946) using the 
0.36m robotic telescope located at Nanshan, Xinjiang, China. 
Observations started at 18:37:21 UT on 2017-10-01, i.e, 701 sec after 
the BAT trigger, and all imaged were taken without filter.

The optical afterglow was detected at the XRT position (Evans et al., 
GCN 21952) with coordinates

R.A. (J2000) = 01:28:18.67
Dec. (J2000) = -11:53:39.0

with an uncertainty of ~0.5 arcsec.

Our photometry was summarized as follows:
========================================
Tmid(s)+T0   Exptime(s)       Mag(R)           MagErr

741                40*2            >17.60

902                60*2              17.93              0.13

1102              60*3              18.00              0.11

1328              90*2              18.55              0.11

1522              90*2              18.60              0.20

3327              90*8             >18.75
========================================
Note: (1) Photometry is calibrated with stars in the USNO B1 catalogue 
in the R-filter, although images were taken without filter. (2) MagErr 
is the only statistical error of the measurement. (3) The magnitudes are 
not corrected for the Galactic extinction.


GRB_name: GRB171001A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21958
SUBJECT: GRB 171001A: Swift-BAT refined analysis
DATE:    17/10/02 14:11:12 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171001A (trigger #775553)
(Lien et al., GCN Circ. 21946).  The BAT ground-calculated position is
RA, Dec = 22.080, -11.928 deg which is
  RA(J2000)  =  01h 28m 19.2s
  Dec(J2000) = -11d 55' 39.6"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 72%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T+11 s and ends at ~T+37 s. The major peaks occur at ~T+13 s, ~T+17 s,
and ~T+32 s, respectively. T90 (15-350 keV) is 22.8 +- 2.0 sec (estimated
error including systematics).

The time-averaged spectrum from T+11.40 to T+37.02 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.48 +- 0.19.  The fluence in the 15-150 keV band is 6.4 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+31.42 sec in the 15-150 keV band
is 0.9 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/775553/BA/


GRB_name: GRB171001A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21959
SUBJECT: GRB 171001A: RATIR Optical and NIR Observations
DATE:    17/10/02 15:46:07 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), JesÃºs
GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:

We observed the field of GRB 171001A (Lien, et al., GCN 21946) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/10 2.17 to 2017/10 2.51 UTC (9.63 to
17.69 hours after the BAT trigger), obtaining a total of 5.31 hours
exposure in the r and i bands and 2.24 hours exposure in the Z, Y, J, and H
bands.

We do not detect a source within the XRT error region (Evans, et al., GCN
21952) or at the position of the Nanshan optical transient (Tan, et al.,
GCN 21957).  In comparison with the USNO-B1 and 2MASS catalogs, we obtain
the following upper limits (3-sigma):

 r > 24.15
 i > 23.98
 Z > 22.96
 Y > 22.77
 J > 22.43
 H > 22.03

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB171003A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21960
SUBJECT: GRB 171003A: Swift detection of a burst or a Galactic Transient
DATE:    17/10/03 03:22:38 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

S. B. Cenko (GSFC), S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU)
and A. Tohuvavohu (PSU) report on behalf of the Swift Team:

At 02:37:00 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171003A (trigger=775946).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 40.910, +61.408, which is 
   RA(J2000)  =  02h 43m 38s
   Dec(J2000) = +61d 24' 28"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical for image triggers, the real-time
light curve does not show anything significant. 

The XRT began observing the field at 02:43:29.0 UT, 388.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 40.9186, 61.4323 which is equivalent to:
   RA(J2000)  = +02h 43m 40.46s
   Dec(J2000) = +61d 25' 56.3"
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This
location is 88 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 1.29e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 400 seconds after the BAT trigger. No credible
afterglow candidate has  been found in the initial data products. The
2.7'x2.7' sub-image covers 100% of  the XRT error circle. The typical
3-sigma upper limit has been about 19.6 mag.  The 8'x8' region for the
list of sources generated on-board covers 100% of the  XRT error
circle. The list of sources is typically complete to about 18 mag. No 
correction has been made for the large, but uncertain extinction
expected. The analysis is complicated by the proximity of a known star
with a USNO V magnitude of 12.01 approximately 7.7 arc-seconds from
the XRT position. 

Based on this source's proximity to the Galactic plane 
(latitude=1.4 degrees) and the duration of the BAT image trigger
(>5 minutes), there is a possibility that this is a
Galactic transient (i.e. Swift J0243.6+6124) rather than a GRB.  
The nature of this source will be determined by the full downloaded
dataset and further observations. 

Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB171003A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21961
SUBJECT: GRB 171003A: LT early optical observations
DATE:    17/10/03 10:34:35 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), 
A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), T. Laskar (UC Berkeley) 
on behalf of a large collaboration report:

The Liverpool Telescope automatically began observing Swift possible GRB 
171003A (Cenko et al. GCN 21960) on October 03, 02:51:26 UT (14 minutes 
after the GRB trigger time) with RINGO3 polarimeter and IO:O camera in 
the SDSS R filter. In addition to the presence of a couple of catalogued 
bright objects, within the Swift-XRT error circle we very marginally 
detect a possible faint, uncatalogued object at the following position:

RA(J2000) = 02:43:40.65
DEC(J2000)= +61:25:53.6

at ~9" from the bright stars above mentioned, with an error radius of 
about 1" and a magnitude of r'=21.3 +- 0.3 (in a 6x10s frame at 48 
minutes post GRB), as calibrated against Pan-STARRS field stars. The 
same possible source is not detected by us earlier, at a mid time of 19 
minutes post GRB down to r'>20.5 mag. Combining the two measures, a 
corresponding upper limit of alpha<0.8 is obtained on the average 
power-law decay index.


GRB_name: GRB171003A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21963
SUBJECT: Swift Trigger 775946 is a Galactic transient, not GRB 171003
DATE:    17/10/03 11:44:51 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

J.A. Kennea (PSU) and S.B. Cenko (NASA/GSFC) report on behalf of the 
Swift Team:

BAT trigger 775946 (GCN #21960) is confirmed to be a Galactic Transient, 
Swift J0243.6+6124. Swift/XRT observations show the source to continue
to be bright with evidence of brightening over three orbits of
observations. We note also a reported possible detection of brightening
of LSI +61 303 by MAXI (ATEL #10803) is likely due to this new transient
(LSI +61 303 is 25 arc-minutes away from the XRT position reported in 
GCN #21960).


GRB_name: GRB171003A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21965
SUBJECT: GRB 171003A: Enhanced Swift-XRT position
DATE:    17/10/03 14:29:33 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1963 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 171003A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 40.91793, +61.43411 which is equivalent
to:

RA (J2000): 02h 43m 40.30s
Dec (J2000): +61d 26' 02.8"

with an uncertainty of 1.5 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB171004A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21966
SUBJECT: GRB 171004A: Swift detection of a burst
DATE:    17/10/04 08:20:31 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

S. B. Cenko (GSFC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL),
P. A. Evans (U Leicester), J.D. Gropp (PSU), K. L. Page (U Leicester)
and M. H. Siegel (PSU) report on behalf of the Swift Team:

At 07:55:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171004A (trigger=776347).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 139.162, +52.680, which is 
   RA(J2000)  =  09h 16m 39s
   Dec(J2000) = +52d 40' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical for image triggers, there is nothing
significant in the real-time light curve. 

The XRT began observing the field at 07:58:26.9 UT, 174.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 139.1713, 52.6937 which is equivalent to:
   RA(J2000)  = +09h 16m 41.11s
   Dec(J2000) = +52d 41' 37.3"
with an uncertainty of 4.9 arcseconds (radius, 90% containment). This
location is 53 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 3.22e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of  52 seconds with the White filter
starting 184 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.02. 

Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170710A
Detection_method: LCO
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21967
SUBJECT: GRB 170710A: LCO Observations
DATE:    17/10/04 12:24:38 GMT
FROM:    Antonino Cucchiara at UVI  <antonino.cucchiara@uvi.edu>

A. Cucchiara (U. Virgin Islands) report on behalf of a larger
collaboration:

"On July 10.05 UT  (T_0 +30 min) we began observing the
center of the field of GRB 170710A (Evans et al.
GCN 21308, Osborne et al. GCN 21310) using the Las Cumbres
Observatory 1m telescope located in Cerro Tololo.

We performed a series of 10x60s observations in SDSS I band
for a total of 10 minutes on sky.

In the full median stacked images we identified no optical
counterpart at the location of the optical counterpart
(Cucchiara et al. GCN 21311, Breeveld et al. GCN 21315).

Nevertheless, at the OT location we identified a
2-sigma excess corresponding to I=21.28 +- 0.24 mag, consistent
with other observations at similar time post-burst.

These magnitudes are calibrated against nearby USNO-B1 sources,
and not corrected for Galactic extinction."


GRB_name: GRB171004A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21968
SUBJECT: GRB 171004A: RATIR Optical and NIR Observations 
DATE:    17/10/04 13:26:20 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki
Toy (UMD) report:

We observed the field of GRB 171004A (Cenko et al., GCN Circ. 21966)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
AstronÃ³mico Nacional on Sierra San Pedro MÃ¡rtir from 2017/10 4.45 to
2017/10 4.45 to 2017/10 4.52 UTC (2.97 to 4.45 hours after the BAT
trigger), obtaining a total of 1.07 hours exposure in the r and i bands
and 0.45 hours exposure in the Z, Y, J, and H bands.

We detect two sources within the Swift-XRT error circle. One is a
cataloged SDSS source. The other is at 09:16:40.66 +52:41:30.4 (J2000
+/- 0.5 arcsec) and, in comparison with the SDSS DR9 and 2MASS catalogs,
has

  r = 21.91 +/- 0.11
  i = 21.32 +/- 0.07
  Z = 21.13 +/- 0.15
  Y = 20.43 +/- 0.12
  J = 20.45 +/- 0.15
  H = 19.88 +/- 0.13

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB171004A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21970
SUBJECT: GRB 171004A: Enhanced Swift-XRT position
DATE:    17/10/04 17:32:21 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2218 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 171004A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 139.16941, +52.69319 which is equivalent
to:

RA (J2000): 09h 16m 40.66s
Dec (J2000): +52d 41' 35.5"

with an uncertainty of 1.4 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB171004A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21971
SUBJECT: GRB 171004A: Swift-XRT refined Analysis
DATE:    17/10/04 18:21:58 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia
(ASDC), A. D'Ai (INAF-IASFPA), S. J. LaPorte (PSU), J.A. Kennea (PSU),
B. Sbarufatti (INAF-OAB/PSU), P.A. Evans (U. Leicester), S.L. Gibson
(U. Leicester) and S.B. Cenko report on behalf of the Swift-XRT team:

We have analysed 7.5 ks of XRT data for GRB 171004A (Cenko et al. GCN
Circ. 21966), from 164 s to 17.4 ks after the  BAT trigger. The data
comprise 296 s in Windowed Timing (WT) mode (the first 9 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Osborne et
al. (GCN Circ. 21970).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.1 (+/-0.4). At T+205 s  the decay
steepens to an alpha of 4.1 (+0.9, -0.8). The light curve breaks again
at T+524 s to a decay with alpha=0.3 (+0.5, -1.3),  before a final
break at T+5520 s s after which the decay index is 2.25 (+0.26, -0.16).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.25 (+/-0.08). The
best-fitting absorption column is  2.41 (+0.28, -0.27) x 10^21 cm^-2,
in excess of the Galactic value of 1.5 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.98 (+/-0.11) and a
best-fitting absorption column of 8.8 (+2.8, -2.7) x 10^20 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.3 x 10^-11 (4.0 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      8.8 (+2.8, -2.7) x 10^20 cm^-2
Galactic foreground: 1.5 x 10^20 cm^-2
Excess significance: 4.5 sigma
Photon index:      1.98 (+/-0.11)

If the light curve continues to decay with a power-law decay index of
2.25, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.9 x
10^-14 (8.3 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00776347.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB171004A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21972
SUBJECT: GRB 171004A: Correction to RATIR Astrometry and Photometry 
DATE:    17/10/04 20:04:21 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki
Toy (UMD) report:

The position and magnitudes of the uncataloged source reported by Watson
et al. (GCN Circ. 21968) are incorrect. We thank David Alexander Kann
for drawing our attention to this error.

The correct position is RA, Dec = 139.169462 52.693080 (J2000) or
09:16:40.67 +52:41:35.1. This position lies 0.4 arcsec from the enhanced
XRT position (Osborne et al., GCN Circ. 21970).

The correct magnitudes are

 r = 21.17 +/- 0.06
 i = 20.87 +/- 0.05
 Z = 20.72 +/- 0.10
 Y = 20.59 +/- 0.13
 J = 20.36 +/- 0.14
 H = 20.17 +/- 0.17

A fit to the i-band light curve of the source shows that the flux
behaves as t^(-0.9+/-0.4). That is, it is fading at the 2-sigma level.

The positional coincidence combined with the weak evidence for fading
suggest that this source might well be the afterglow of the GRB.


GRB_name: GRB171004A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21973
SUBJECT: GRB 171004A: Swift-BAT refined analysis
DATE:    17/10/04 21:13:14 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), 
S. B. Cenko (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171004A (trigger #776347)
(Cenko et al., GCN Circ. 21966).  The BAT ground-calculated position is
RA, Dec = 139.150, 52.684 deg which is 
   RA(J2000)  =  09h 16m 35.9s 
   Dec(J2000) = +52d 41' 01.5" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 42%.
 
The mask-weighted light curve shows several overlapping peaks that starts
at ~ T+9 and ends at ~ T+160 s. The burst location went out of the BAT FOV
at ~ T+580 s, and thus we only have information of the burst emission before
then. T90 (15-350 keV) is 107.1 +- 14.5 sec (estimated error including 
systematics).
 
The time-averaged spectrum from T+9.08 to T+138.31 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.67 +- 0.12. The fluence in the 15-150 keV band is 3.0 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+48.34 sec in the 15-150 keV band
is 0.9 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/776347/BA/


GRB_name: GRB171004A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21974
SUBJECT: GRB 171004A: Swift/UVOT Upper Limits
DATE:    17/10/05 14:03:40 GMT
FROM:    Jeffrey Gropp at PSU  <jdg44@psu.edu>

J. D. Gropp (PSU) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 171004A
184 s after the BAT trigger (Cenko et al., GCN Circ. 21966).
No optical afterglow consistent with the refined XRT position
(Osborne et al. GCN Circ. 21970)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white              184         4143          233         >20.3
b                 3903         4103          197         >19.8
u                 3698         3898          197         >19.7


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB171007A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21976
SUBJECT: GRB 171007A: Swift detection of a burst
DATE:    17/10/07 12:14:34 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

J. K. Cannizzo (NASA/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (NASA/UMBC), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of
the Swift Team:

At 11:57:38 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171007A (trigger=777215).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 135.544, +42.849, which is 
   RA(J2000)   = 09h 02m 10s
   Dec(J2000) = +42d 50' 57"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several peaks
with a total duration of about 25 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 11:58:47.2 UT, 68.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
135.6006, 42.8195 which is equivalent to:
   RA(J2000)  = 09h 02m 24.15s
   Dec(J2000) = +42d 49' 10.3"
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This
location is 183 arcseconds from the BAT onboard position, at the edge of 
the BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 2.05
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 6.22e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 77 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.02. 

Burst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB171007A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21977
SUBJECT: GRB 171007A: RATIR Optical and NIR Observations
DATE:    17/10/07 14:39:05 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), JesÃºs
GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:

We observed the field of GRB 171007A (Cannizzo, et al., GCN 21976) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/10 7.50 to 2017/10 7.52 UTC (3 minutes to
0.57 hours after the BAT trigger), obtaining a total of 0.31 hours exposure
in the r and i bands and 0.14 hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):

 r > 22.05
 i > 21.94
 Z > 21.24
 Y > 21.02
 J > 20.65
 H > 20.34

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB171007A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21978
SUBJECT: GRB 171007A: Swift-XRT refined Analysis
DATE:    17/10/07 17:55:02 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), J.A.
Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), P.A.
Evans (U. Leicester), S.L. Gibson (U. Leicester), J.P. Osborne (U.
Leicester) and J.K. Cannizzo report on behalf of the Swift-XRT team:

We have analysed 6.1 ks of XRT data for GRB 171007A (Cannizzo et al.
GCN Circ. 21976), from 62 s to 12.7 ks after the  BAT trigger. The data
comprise 107 s in Windowed Timing (WT) mode (the first 5 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The best available XRT position  (using the promptly downlinked
event data, the XRT-UVOT alignment and matching UVOT field sources to
the USNO-B1 catalogue) is RA, Dec = 135.6008, 42.8193 which is
equivalent to:

RA (J2000): 09 02 24.19
Dec(J2000): +42 49 09.5

with an uncertainty of 2.3 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=3.56 (+0.21, -0.18).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.38 (+0.19, -0.18). The
best-fitting absorption column is  1.2 (+0.9, -0.7) x 10^21 cm^-2, in
excess of the Galactic value of 2.1 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.7 x 10^-11 (5.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:      1.2 (+0.9, -0.7) x 10^21 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 2.4 sigma
Photon index:      1.38 (+0.19, -0.18)

If the light curve continues to decay with a power-law decay index of
3.56, the count rate at T+24 hours will be 1.1 x 10^-10 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.2 x
10^-21 (5.7 x 10^-21) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00777215.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB171007A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21979
SUBJECT: GRB 171007A: Enhanced Swift-XRT position
DATE:    17/10/07 18:09:49 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1637 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 171007A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 135.60048, +42.81920 which is equivalent
to:

RA (J2000): 09h 02m 24.11s
Dec (J2000): +42d 49' 09.1"

with an uncertainty of 2.0 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB171007A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21980
SUBJECT: GRB 171007A: Fermi GBM observation
DATE:    17/10/07 22:45:12 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

Elisabetta Bissaldi (Politecnico & INFN Bari)
reports on behalf of the Fermi GBM Team:

"At 11:57:39.90 UT on 07 October 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171007A (trigger 529070264 / 171007498),
which was also detected by the Swift-BAT (Cannizzo et al. 2017, GCN 21976).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 50 degrees.

The GBM light curve consists of single peak
with a duration (T90) of about 3.5 s (50-300 keV).
The time-averaged spectrum from T0-1.4 s to T0+2.1 s is
adequately fit by a simple power law function with
index -1.31 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(6.1 +/- 0.7)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1 s in the 10-1000 keV band
is 1.5 +/- 0.2 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB171007A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21981
SUBJECT: GRB 171007A: Swift-BAT refined analysis
DATE:    17/10/08 16:57:32 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC), J. K. Cannizzo (NASA/UMBC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
J. P. Norris (BSU), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171007A (trigger #777215)
(Cannizzo et al., GCN Circ. 21976).  The BAT ground-calculated position is
RA, Dec = 135.635, 42.930 deg which is
  RA(J2000)  =  09h 02m 32.5s
  Dec(J2000) = +42d 55' 47.4"
with an uncertainty of 3.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a short spike that start at ~ T-0.1 s and
ends at ~ T+2.9 s. There is some weak emission lasting till ~T+80 s.
T90 (15-350 keV) is 105 +- 45 sec (estimated error including systematics).

The time-averaged spectrum from T-0.08 to T+107.92 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.38 +- 0.52.  The fluence in the 15-150 keV band is 2.9 +- 1.1 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.92 sec in the 15-150 keV band
is 0.4 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

Although the burst is weak and the short spike is ~ 3 s, the structure of the burst
shows similarity to those of short GRBs with extended emission. We thus perform
further analysis on the short spike and the tail emission. The spectrum of the short
spike from T-0.08 to T+2.92 sec is best fit by a simple power-law model, with
power-law index of 0.83 +- 0.35 and fluence (15-150 keV) of 1.0 +- 0.2 x 10^-7 erg/cm2.
The spectrum of the tail emission from T+2.92 to T+107.92 sec is best fit by a simple
power-law model, with power-law index of 1.67 +- 0.73 and fluence (15-150 keV) of
1.8 +- 1.0 x 10^-7 erg/cm2. These values are consistent with those of short GRBs with
extended emission (Lien & Sakamoto et al. 2016).

The lag analysis is unconstrained due to the weakness of this burst.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/777215/BA/


GRB_name: GRB171007A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21984
SUBJECT: GRB 171007A: Swift/UVOT Upper Limits
DATE:    17/10/10 16:42:31 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and J. K. Cannizzo (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 171007A
77 s after the BAT trigger (Cannizzo et al., GCN Circ. 21976).
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al. GCN Circ. 21979)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            77          227          147         >20.7
u_FC               291          540          246         >20.4
white               77         6966          805         >21.7
v                  620         7377          529         >19.5
b                  546         6761          510         >20.8
u                  291         6556          559         >20.7
w1                 669         6351          333         >20.3
m2                 644         7572          480         >19.9
w2                 596         7172          529         >20.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB171010A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21985
SUBJECT: GRB 171010A: Fermi-LAT detection
DATE:    17/10/11 00:42:09 GMT
FROM:    Nicola Omodei at Stanford U.  <nicola.omodei@slac.stanford.edu>

N. Omodei (Stanford U.), G. Vianello (Stanford U.), B. Ahlgren (KTH)

report on behalf of the Fermi-LAT team:

At 19:00:50.58 on October, 10, 2017 Fermi-LAT detected high-energy emission from GRB 171010A, which was also detected by Fermi-GBM (trigger 529354855 / 171010792). 

The best LAT on-ground location is found to be:
 RA, Dec = 66.74, -10.53 (J2000) 
 with an error radius of 0.20 deg (90 % containment, statistical error only). 

The GRB was outside the LAT field of view at the time of the GBM trigger and triggered an autonomous repoint of the spacecraft.

The data from the Fermi-LAT show a significant increase in the event rate that is spatially correlated with the trigger with high significance. 

The highest-energy photon is a 7 GeV event which is observed 768 seconds after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is  B. Ahlgren (bjornah@kth.se).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB171010A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21986
SUBJECT: GRB 171010A: Swift ToO observations
DATE:    17/10/11 01:43:18 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Fermi/LAT GRB 171010A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020778

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/LAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB171010A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21987
SUBJECT: GRB 171010A:  OT, spectrum, and possible host galaxy
DATE:    17/10/11 13:27:39 GMT
FROM:    Jules Halpern at Columbia U.  <jules@astro.columbia.edu>

John R. Thorstensen (Dartmouth) and Jules P. Halpern (Columbia) report:

Automated analysis of Swift XRT data (GCN #21986) on Fermi-LAT
GRB 171010A (GCN #21985) reports a fading X-ray source at:

(J2000) 04:26:19.44 -10:27:47.1  +/- 1.4"

We pointed the 1.3m McGraw-Hill telescope of the MDM Observatory
at this location beginning on 2017 October 11 08:31 UT, 13.5 hr
after the burst, and obtained images in the Cousins R filter that
show a new object at:

(J2000) 04:26:19.48 -10:27:46.2  +/- 0.4"

with position referenced to the PPMXL catalog. In comparison with
nearby stars with r magnitudes from Pan-STARRS, we estimate r = 18.0
at 08:31 UT.  Continuing photometry shows that the OT faded from
r = 18.05 to 18.38 between 8:55 UT and 10:28 UT.

There is also a faint galaxy at this position on the digitized
POSS II and in Pan-STARRS, but bright moon now makes it difficult
to detect in our images.  The Pan-STARRS position of this possible
host galaxy is:

(J2000) 04:26:19.56 -10:27:45.8

Using the 2.4m Hiltner telescope with Modspec, we obtained 17x12 minutes
spectra of the OT covering the wavelength range 4400-7500 A at 4 A
resolution, which when summed show a featureless continuum with a
signal-to-noise ratio of about 50 per 2 A pixel.


GRB_name: GRB171010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21988
SUBJECT: GRB 171010A: optical observations
DATE:    17/10/11 13:45:16 GMT
FROM:    Luca Izzo at IAA-CSIC  <Luca.Izzo@ICRA.it>

L. Izzo (IAA-CSIC) and D. Malesani (DARK/NBI) report:

We observed the field of the Fermi LAT GRB 171010A (Omodei et al., GCN 21985) with the T24 (Plane Wave CDK 0.61m) of the iTelescope.Net <http://itelescope.net/> (http://www.itelescope.net <http://www.itelescope.net/>) located at Auberry (CA, USA).

A set of three images of 300 s each was taken in the I filter, starting on October 11th at 09:55:32 UT, ~14.9 hr after the LAT GRB trigger. In particular, we inspected the position of the X-ray candidate found by XRT (Evans, GCN 21986), reported at http://www.swift.ac.uk/ToO_GRBs/00020778 <http://www.swift.ac.uk/ToO_GRBs/00020778> . Inside the UVOT-enhanced XRT position, we detect a source at coordinates (J2000):

RA = 04:26:19.46
DEC = -10:27:45.9

This position is 1.3" W of an object with i = 20.31 +- 0.05 (AB) visible in the Pan-STARRS archival images. We measure for the source I = 17.85 +- 0.20 mag (AB)

The difference in brightness with respect to the archival Pan-STARRS source, as well as the association with the XRT counterpart, suggests the presence of an additional source which we believe to be due to the GRB afterglow. The Pan-STARRS object could be the host galaxy of the GRB, as also suggested in Thorstensen et al. (GCN 21987), or an unrelated source.

Additional observations are very welcome.


GRB_name: GRB171010A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21989
SUBJECT: GRB 171010A: Swift-XRT afterglow detection
DATE:    17/10/11 13:48:44 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti
(INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S.L. Gibson
(U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
P. D'Avanzo (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf
of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 171010A (Omodei et al. GCN Circ. 21985),
collecting 5.0 ks of Photon Counting (PC) mode data between T0+24.2 ks
and T0+41.7 ks. 

Four uncatalogued X-ray sources are detected, of which one ("Source 2")
is above the RASS limit, and is therefore likely the GRB afterglow.
Using 4537 s of PC mode data and 7 UVOT images, we find an enhanced XRT
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 66.58092, -10.46325 which is
equivalent to:

RA (J2000): 04h 26m 19.42s
Dec(J2000): -10d 27' 47.7"

with an uncertainty of 1.4 arcsec (radius, 90% confidence). This
position is 10.5 arcmin from the Fermi/LAT position. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=2.2 (+/-0.3).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.01 (+/-0.15). The
best-fitting absorption column is  3.6 (+0.7, -0.6) x 10^21 cm^-2, in
excess of the Galactic value of 7.0 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.3 x 10^-11 (5.0 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.6 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 7.0 x 10^20 cm^-2
Excess significance: 7.4 sigma
Photon index:      2.01 (+/-0.15)

If the light curve continues to decay with a power-law decay index of
2.2, the count rate at T+24 hours will be 0.054 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x
10^-12 (2.7 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020778.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00020778.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB171010A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21990
SUBJECT: GRB171010A: AstroSat CZTI detection
DATE:    17/10/11 14:13:28 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:

Analysis of Astrosat CZTI data showed the detection of a long-duration bright GRB 171010A, which was also detected by Fermi-GBM (trigger 529354855 / 171010792) and Fermi-LAT (Omodei N. et al, GCN # 21985).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peak emission with strongest peak at 19:01:24.58 UT, ~34 s after the Fermi Trigger. The measured peak count rate is 2001.9 cts/s above the background in combined data of four quadrants, with a total of 61101 cts. The local mean background count rate was 333.1 cts/s. Using cumulative rates, we measure a T90 of 70.3 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB171010A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21991
SUBJECT: GRB 171010A: LCO 1m telescope observations
DATE:    17/10/11 14:17:15 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), 
A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large 
collaboration report:

We began observing Fermi LAT GRB 171010A (Omodei et al. GCN 21985) on 
October 11, from 02:15 to 02:28 UT (7.2 hours since the GRB trigger 
time) with one of the 1-m LCO telescopes in Sutherland in the SDSS-I 
filter. Within the enhanced Swift-XRT circle (D'Ai et al. GCN 21989) we 
clearly detect the optical afterglow (Thorstensen and Halpern, GCN 
21987; Izzo and Malesani, GCN 21988) with the following magnitude:

Mid Time Exposure Filter Magnitude (AB)
(hrs) (s)
-------------------------------------------------------
7.3 5x120 SDSS-I 16.82 +- 0.02
-------------------------------------------------------

as calibrated against nearby Pan-STARRS objects.


GRB_name: GRB171010A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21992
SUBJECT: GRB 171010A: Fermi GBM observation
DATE:    17/10/11 16:33:18 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Poolakkil and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 19:00:50.58 UT on 10 October 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171010A (trigger 529354855 / 171010792)
which was also detected by Fermi LAT (N. Omodei et al. 2017, GCN 21985) and
AstroSat (Sharma et al, GCN 21990). The afterglow was observed by Swift-XRT
(A. D'Ai  et al. 2017, GCN 21989). The GBM on-ground location is consistent
with
the LAT position.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux of the GRB.
This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the best location is 113 degrees.

The GBM light curve consists of several episodes
with a duration (T90) of about 104 s (50-300 keV).
The time-averaged spectrum from T0+5.12 s to T0+151.55 s is
best fit by a Band function with Epeak = 154 +/- 1 keV, alpha = -1.11 +/-
0.01
and beta = -2.22 +/- 0.01.

The event fluence (10-1000 keV) in this time interval is
6.42E-04 +/- 1.5E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+68.16 s in the 10-1000 keV band
is 117.5 +/- 1.02 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB171011A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21993
SUBJECT: GRB 171011A: Swift detection of a burst
DATE:    17/10/11 18:40:36 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J.D. Gropp (PSU), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL) and B. Sbarufatti (PSU)
report on behalf of the Swift Team:

At 18:32:47 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171011A (trigger=778154).  Swift could not slew to the burst
due to the Sun observing constraint. 
The BAT on-board calculated location is 
RA, Dec 236.761, -10.071 which is 
   RA(J2000) = 15h 47m 03s
   Dec(J2000) = -10d 04' 14"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single peak
structure with a duration of about 5 sec.  The peak count rate
was ~10,000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 11:46 UT on 2018 January 03. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB171011A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21994
SUBJECT: GRB 171011A: MASTER-SAAO optical observations
DATE:    17/10/11 19:12:29 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, A.V.Krylov,
I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA),
National University of San Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk,
Irkutsk State University

V.Yurkov, Yu.Sergienko
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was pointed to the  GRB171011A 34 sec after notice time 
and 273 sec after trigger time at 2017-10-11 18:37:20 UT. On our first 
(50s exposure)  set we  not found  optical transient within SWIFT 
error-box  (ra=236.758 dec=-10.0703 r=0.1) brighter then 17.7.


The observations made on zenit distance = 80 degrees, galaxy latitude b = 
33 degree.
The moon (59 % bright part) below the horizon (The altitude of the Moon is 
-51 degree ).
The sun  altitude  is -23.4 degree.
The error box can be observed till sunrise at 2017-10-12 03:59:47.

This message can be cited.


GRB_name: GRB171010B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21995
SUBJECT: GRB 171010B: Swift detection of a burst 
DATE:    17/10/11 19:18:11 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL) and A. Y. Lien (GSFC/UMBC),
report on behalf of the Swift team:

At 20:59:24.168 UT on 2017-10-10, the Swift Burst Alert Telescope (BAT) triggered on
GRB 171010B (trigger=778019). However, on-board analysis was truncated by
a pre-planned slew to a scheduled target.  Subsequent ground analysis
using data from T+1 to T+11 s finds the source at a location of
RA, Dec = 34.123, -54.410 deg which is 
  RA(J2000)  =  02h 16m 29.6s 
  Dec(J2000) = -54d -24' -36.7" 
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.

The BAT light curve shows a single-peaked structure that starts and peaks at ~T0, 
and ends at ~ T+30 s. Because the burst was not identified on board, the event 
data available (~T+1 to ~T+11) do not cover the entire burst duration.
T90 estimated from the BAT raw light curve (15-350 keV) is about 30.4 s.

The time-averaged spectrum from T+1.0 to T+11.1 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.41 +- 0.18.  The fluence in the 15-150 keV band is 3.9 +- 0.5 x 10^-7 erg/cm2.
All the quoted errors are at the 90% confidence level.

This event was also detected by Fermi/GBM (trigger 529361971).

A Swift Target of Opportunity observation has been requested.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/778019/BA/


GRB_name: GRB171011A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21996
SUBJECT: GRB 171011A: TAROT Calern observatory optical observations
DATE:    17/10/11 21:25:44 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Noysena.K., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Eymar, L. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:

We imaged the field of GRB 171011A detected by SWIFT
(trigger 778154) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 41.5s after the GRB trigger
(12.6s after the notice). The elevation of the field
decreased from 7 degrees above horizon and weather
conditions were good.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+41.5s to t0+101.5s : Rlim = 16.3

The second image is 30.0s exposure in tracking mode:
t0+114.1s to t0+144.1s : Rlim = 16.6

We co-added a series of exposures:
t0+114.1s to t0+405.3s : Rlim = 17.4

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB171010B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21997
SUBJECT: GRB 171010B: Swift ToO observations
DATE:    17/10/11 22:17:14 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Swift/BAT GRB 171010B. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020780

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB171011B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21998
SUBJECT: IPN Triangulation of GRB 171011B (long/very bright)
DATE:    17/10/11 22:58:57 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration, very bright GRB 171011B was detected
by Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND),
and Swift (BAT) at about 3935 s UT (01:05:35).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   158.860 (10h 35m 26s)  +1.646 ( +1d 38' 46")
  Corners:
   159.793 (10h 39m 10s)  -2.035 ( -2d 02' 06")
   158.437 (10h 33m 45s)  +4.418 ( +4d 25' 05")
   158.940 (10h 35m 46s)  +6.060 ( +6d 03' 36")
   159.687 (10h 38m 45s)  -0.726 ( +0d 43' 33")
  ---------------------------------------------
The error box area is 2.646 sq. deg, and its maximum
dimension is 8.14 deg (the minimum one is 23.5 arcmin).
The Sun distance was 37 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB171011_T03931/IPN

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB171010B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21999
SUBJECT: GRB 171010B: Fermi GBM detection
DATE:    17/10/12 01:19:00 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Poolakkil and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 20:59:26.48 UT on 10 October 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171010B (trigger 529361971/ 171010875)
which was also detected by Swift-BAT (D. M. Palmer et al,GCN 21995). The
GBM
on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger
time is 50 degrees.

The GBM light curve consists of several episodes
with a duration (T90) of about 25s (50-300 keV).
The time-averaged spectrum from T0-2.05 s to T0+6.14 s is
best fit by by a simple power law function with
index -1.66 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(8.073 +/- 1.802)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.85 s in the 10-1000 keV band is 1.41 +/- 0.15 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

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GRB_name: GRB171010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22000
SUBJECT: GRB 171010A: NOT optical observations
DATE:    17/10/12 01:44:15 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DARK/NBI), K. E. Heintz (Univ. Iceland and DARK/NBI), P. 
Calissendorff (Stockholm Univ), and I. R. Losada (NOT) report on behalf 
of a larger collaboration:

We observed the optical counterpart (Thorstensen & Halpern, GCN 21987; 
Izzo & Malesani, GCN 21988; Guidorzi et al., GCN 21991) of the Fermi GRB 
171010A (Poolakkil & Meegan, GCN 21992; Omodei et al., GCN 21985) with 
the Nordic Optical Telescope equipped with the StanCam imager. 
Observations were carried out in the Johnson-Cousins BVRI filters.

The optical counterpart is well detected in our images. Using the 
Pan-STARRS catalog as reference, we measure a magnitude r = 19.18 +- 
0.06 AB at an epoch Oct 12.03 UT (29.74 hr after the trigger).

Comparing our measurement with the report by Thorstensen & Halpern (GCN 
21987) we infer a decay index alpha = 1.4 assuming an unbroken power-law 
decay.


GRB_name: GRB171010A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22001
SUBJECT: GRB 171010A: MITSuME Akeno Optical Observation
DATE:    17/10/12 02:53:40 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata@u.phys.nagoya-u.ac.jp>

S. Harita, R. Itoh, K. L. Muarata, Y. Tachibana, T. Yoshii, K. Morita, T.
Ozawa, H. Mamiya, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We have been observing the optical counterpart of GRB 171010A (N. Omodei et
al., GCN Circular #21985) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan.

The observation started on 2017-10-11 13:29:52.24 UT.
We detected the previously reported optical afterglow (Thorstensen &
Halpern, GCN Circular #21987; Izzo & Malesani, GCN Circular #21988;
Guidorzi et al., GCN Circular #21991; Malesani et al., GCN Circular #22000)
in Ic and Rc bands.
The measured magnitudes were listed as follows.

T0+[hour]    MID-UT      T-EXP[sec]         g'              Rc
       Ic
-------------------------------------------------------------------------------------------------------
~18.29         15:23:32          4380           >18.8    18.04+/- 0.16
 17.331 +/- 0.12
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB171010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22002
SUBJECT: GRB 171010A: ePESSTO NTT spectroscopic redshift
DATE:    17/10/12 11:14:14 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

E. Kankare (QUB), D. O'Neill (QUB), L. Izzo (IAA-CSIC), V. D'Elia (ASI/ASDC), S. D. Vergani (GEPI/Obs. Paris), 
D. Malesani (DARK/NBI), K. E. Heintz (Univ. Iceland & DARK/NBI), P. Schady (MPE), A. Melandri, P. D'Avanzo, 
S. Campana, S. Covino (INAF-OAB), M. Magee (QUB), T.-W Chen (MPE), L. Galbany (U. Pittsburgh), C. Inserra 
(Southampton), K. Maguire (QUB), S. Smartt (QUB), O. Yaron (Weizmann), D. Young (QUB), I. Manulis (Weizmann) report:


We observed the optical afterglow of GRB 171010A (Thorstensen & Halpern, GCN 21987; Izzo & Malesani, 
GCN 21988; Guidorzi et al., GCN 21991; Malesani et al. GCN 22000; Harita et al. GCN 22001) under the 
extended Public ESO Spectroscopic Survey for Transient Objects (ePESSTO; see Smartt et al. 2015, A&A, 
579, 40 http://www.pessto.org <http://www.pessto.org/> ). The observations were performed on the ESO New Technology Telescope 
at La Silla with the EFOSC2 instrument in spectroscopic mode starting from 2017-10-12 at 07:05:01 UT 
(i.e. 36.1 hours from the burst) and using the Grism 13 (3985-9315 AA, 18 AA resolution). Both the optical 
afterglow and the object visible in the Pan-STARRS archival images lying 1.3â€ away (suggested as the 
possible host galaxy by Thorstensen & Halpern, GCN 21987 and Izzo & Malesani, GCN 21988) were included 
in the slit. 

In the acquisition image, the optical afterglow is clearly detected with a magnitude of R(AB)~19.3.

The optical spectrum shows emission features which we identify as [O II], Hbeta, [O III], and Halpha at a 
common redshift z=0.33. No clear absorption features are detected, in agreement with the report by 
Thorstensen & Halpern (GCN 21987). The lack of detection of absorption features in high-S/N spectra is 
strongly suggestive of a low redshift for the afterglow. Combined with the proximity to the archival object, 
we suggest that z = 0.33 is the redshift of GRB 171010A. Further analysis is in progress.


GRB_name: GRB171010A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22003
SUBJECT: Konus-Wind observation of GRB 171010A
DATE:    17/10/12 11:50:56 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The long, very bright GRB 170410A (Fermi-LAT detection: Omodei et al.,
GCN 21985; Fermi-GBM detection: Poolakkil and Meegan, GCN 21992)
triggered Konus-Wind at T0=68460.142 s UT (19:01:00.142)

The burst light curve shows a bright, multi-peaked pulse,
with a total duration of ~155 s (from ~T0-8 s -- ~T0+147 s),
which was preceded by a weaker emission starting from ~T0-150 s.
A much weaker pulse is also seen in the KW light curve around ~T0+250 s.
The emission is seen up to ~15 MeV.

As observed by Konus-Wind, the burst had a fluence of
(6.5 Â± 0.2)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+26.496, of (2.45 Â± 0.17)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+147.968 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.09 (-0.04,+0.04),
the high energy photon index beta = -2.42 (-0.07,+0.06),
the peak energy Ep = 171 (-6,+7) keV,
chi2 = 95/95 dof.

The spectrum near the peak count rate (measured from T0+26.112 s
to T0+27.136 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.75 (-0.06,+0.06),
the high energy photon index beta = -2.58 (-0.22,+0.16),
the peak energy Ep = 273 (-27,+27) keV,
chi2 = 78/70 dof.

Assuming the redshift z=0.33 (Kankare et al., GCN 22002)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.3, and Omega_Lambda = 0.7,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~1.8x10^53 erg,
the peak luminosity L_iso is ~8.8x10^51 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~227 keV.


The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB171010_T68460/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.

[GCN OPS NOTE(12oct17):  Per author's request, the "170410A"
in the first sentence was changed to "171010A".]


GRB_name: GRB171010A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22004
SUBJECT: GRB 171010A: Swift/UVOT Detection
DATE:    17/10/12 13:22:35 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and M. H. Siegel (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 171010A
69338 s after the LAT trigger (Omodei et al., GCN Circ. 21985).
A afterglow (Thorstensen and Halpern, GCN Circ. 21987, Izzo and 
Malesani, GCN Circ. 21988, Guidorzi et al., GCN Circ. 21991, Malesani et 
al., GCN Circ. 22000, Harita et al., GCN Circ. 22001) is detected in the 
initial UVOT exposures. However it is not possible to distinguish this 
source from the position of the Pan-STARRS source given in Izzo and 
Malesani (GCN Circ. 21988). The source magnitude is not changing 
significantly within this observation.

Preliminary detections using the UVOT photometric system (Breeveld et 
al. 2011, AIP Conf. Proc. 1358, 373) for the summed exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white            69338        80991         4818         18.84 Â± 0.02

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.15 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB171011B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22005
SUBJECT: Konus-Wind observation of GRB 171011B
DATE:    17/10/12 13:27:38 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, very intense GRB 171011B
(IPN triangulation: Hurley et al., GCN Circ. 21998)
triggered Konus-Wind at T0=3931.430 s UT (01:05:31.430).

The burst light curve shows a multipeaked structure
which starts at ~T0-7.3 s and has a total duration of ~18.2 s.
The emission is seen up to ~20 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB171011_T03931/

As observed by Konus-Wind, the burst
had a fluence of 7.02(-0.56,+0.57)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.456 s,
of 5.55(-0.61,+0.62)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+10.496 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.54(-0.12,+0.14),
the high energy photon index beta = -2.28(-0.16,+0.12),
the peak energy Ep = 315(-33,+37) keV
(chi2 = 98/97 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+1.792 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.51(-0.11,+0.14),
the high energy photon index beta = -2.59(-0.34,+0.21),
the peak energy Ep = 416(-48,+50) keV
(chi2 = 78/65 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB171011A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22006
SUBJECT: GRB 171011A: Swift-BAT refined analysis
DATE:    17/10/12 14:47:20 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC),
J.D. Gropp (PSU), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-119 to T+54 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171011A (trigger #778154)
(Gropp et al., GCN Circ. 21993).  The BAT ground-calculated position is
RA, Dec = 236.766, -10.064 deg which is
  RA(J2000)  =  15h 47m 03.7s
  Dec(J2000) = -10d 03' 50.2"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 63%.

The mask-weighted light curve shows a single-peaked light curve that
starts and peaks at ~ T0, and ends at ~ T+3 s. T90 (15-350 keV) is
2.27 +- 0.24 sec (estimated error including systematics).

The time-averaged spectrum from T-0.06 to T+2.74 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.68 +- 0.08.  The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.08 sec in the 15-150 keV band
is 7.0 +- 0.4 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/778154/BA/


GRB_name: GRB171010B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22009
SUBJECT: GRB 171010B: Swift-XRT observations
DATE:    17/10/13 12:18:33 GMT
FROM:    Boris Sbarufatti at PSU  <bxs60@psu.edu>

B. Sbarufatti (PSU), J. D. Gropp (PSU), A. Tohuvavohu (PSU), S. J.
LaPorte (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC)
and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 171010B (Palmer et al. GCN Circ. 21995),
collecting 4.8 ks of Photon Counting (PC) mode data between T0+91.1 ks
and T0+120.1 ks. 

One uncatalogued X-ray source has been detected consistent with being
within 96 arcsec of the Swift/BAT position, however it is not above the
RASS limit and does not show definitive signs of fading. Therefore, at
the present time we cannot confirm if it is the afterglow. Details of
the source are given below:

Source 2:
  RA (J2000):  34.1342  =  02:16:32.20
  Dec (J2000): -54.3915  =  -54:23:29.2
  Error: 5.6 arcsec (radius, 90% conf.)
  Count-rate: (6.9 [+1.5, -1.4])e-3 ct s^-1   
  Distance: 71 arcsec from Swift/BAT position.
  Flux: (3.35 [+0.74, -0.68])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)


Six uncatalogued sources were also detected too far from the GRB
position to be likely afterglow candidates.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020780.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB171010A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22011
SUBJECT: GRB 171010A: RATIR Optical and NIR Observations 
DATE:    17/10/13 17:29:22 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Eleonora Troja (GSFC), Nat Butler (ASU),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer
(UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara (UVI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki
Toy (UMD) report:

We observed the field of GRB 171010A (Omodei et al., GCN Circ. 21985)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
AstronÃ³mico Nacional on Sierra San Pedro MÃ¡rtir from 2017/10 13.33 to
2017/10 13.50 UTC (60.79 to 65.05 hours after the LAT trigger),
obtaining a total of 2.72 hours exposure in the r and i bands and 1.13
hours exposure in the Z, Y, J, and H bands.

We detect the afterglow candidate reported by Thorstensen & Halpern (GCN
Circ. 21987), Izzo & Malesani (GCN Circ. 21988), and D'Ai et al. (GCN
Circ. 21989). In comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following magnitudes:

  r = 19.88 +/- 0.02
  i = 19.59 +/- 0.02 
  Z = 19.25 +/- 0.02
  Y = 19.19 +/- 0.02
  J = 18.97 +/- 0.03
  H = 18.80 +/- 0.03

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

Further observations are planned.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro 
MÃ¡rtir.


