| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
6:53:28 UTC |
GCN_circulars,Swift Det |
| ra |
58.8882° |
Swift |
| decl |
12.1819° |
Swift |
| pos_error |
7.25e-05° |
Swift |
| T90 |
1.25 s |
Swift |
| T90_start |
6:53:28 UTC |
Swift |
| fluence |
7.10e-08 erg/cm² |
Swift |
| T100 |
1.25 s |
|
| GBM_located |
False |
|
| mjd |
57962.28712962963 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB170728A |
| ra |
58.8958° |
| decl |
12.1500° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB170728A |
| t_trigger |
6:53:28 UTC |
| ra |
58.8882° |
| decl |
12.1819° |
| pos_error |
7.25e-05° |
| T90 |
1.25 s |
| fluence |
7.10e-08 erg/cm² |
| GCN 21367 table |
|---|
| GRB_name |
GRB170728A |
| GCN_number |
21367 |
| Detection_method |
Swift Det |
| t_trigger |
6:53:28 UTC |
| ra |
58.8980° |
| decl |
12.1530° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21367
SUBJECT: GRB 170728A: Swift detection of a burst
DATE: 17/07/28 07:04:25 GMT
FROM: David Palmer at LANL
J. K. Cannizzo (NASA/UMBC), A. P. Beardmore (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:
At 06:53:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170728A (trigger=765008). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 58.898, +12.153 which is
RA(J2000) = 03h 55m 35s
Dec(J2000) = +12d 09' 11"
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 3 sec. The peak count rate
was ~2400 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 06:54:39.4 UT, 70.6 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 58.88846, 12.18313 which
is equivalent to:
RA(J2000) = 03h 55m 33.23s
Dec(J2000) = +12d 10' 59.3"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 113 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 2.27
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 73 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 0.24.
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.)
|
| GCN 21368 table |
|---|
| GRB_name |
GRB170728A |
| GCN_number |
21368 |
| Detection_method |
Swift-XRT Det |
| ra |
58.8883° |
| decl |
12.1815° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21368
SUBJECT: GRB 170728A: Enhanced Swift-XRT position
DATE: 17/07/28 10:59:59 GMT
FROM: Phil Evans at U of Leicester
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1579 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 170728A, 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 = 58.88831, +12.18148 which is equivalent
to:
RA (J2000): 03h 55m 33.19s
Dec (J2000): +12d 10' 53.3"
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.
|
| GCN 21370 table |
|---|
| GRB_name |
GRB170728A |
| GCN_number |
21370 |
| Detection_method |
Swift-BAT Det |
| ra |
58.9010° |
| decl |
12.1690° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21370
SUBJECT: GRB 170728A: Swift-BAT refined analysis
DATE: 17/07/28 22:55:07 GMT
FROM: Amy Lien at GSFC
M. Stamatikos (OSU), 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), 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 170728A (trigger #765008)
(Cannizzo et al., GCN Circ. 21367). The BAT ground-calculated position is
RA, Dec = 58.901, 12.169 deg which is
RA(J2000) = 03h 55m 36.3s
Dec(J2000) = +12d 10' 07.3"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 73%.
The mask-weighted light curve shows a weak pulse that starts at ~T0 and ends
at ~T+1.5. There is no evidence of extended emission. T90 (15-350 keV)
is 1.25 +- 0.23 sec (estimated error including systematics).
The time-averaged spectrum from T+0.17 to T+1.56 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index -0.49 +- 1.81,
and Epeak of 38.6 +- 7.3 keV (chi squared 51.37 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 7.1 +- 1.4 x 10^-8 erg/cm2
and the 1-sec peak flux measured from T+0.20 sec in the 15-150 keV band is
1.1 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 2.02 +- 0.26 (chi squared 60.76 for 57 d.o.f.). All the quoted errors
are at the 90% confidence level.
The spectrum is on the very soft end of the BAT-detected short GRB, only
a handful of BAT-detected short GRBs have comparable hardness ratio as
this burst (Lien & Sakamoto et al. 2016).
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/765008/BA/
|
| GCN 21378 table |
|---|
| GRB_name |
GRB170728A |
| GCN_number |
21378 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21378
SUBJECT: GRB 170728A: Swift-XRT refined Analysis
DATE: 17/07/29 07:03:35 GMT
FROM: Phil Evans at U of Leicester
J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU),
S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB) and J.K. Cannizzo report on behalf of the Swift-XRT team:
We have analysed 4.8 ks of XRT data for GRB 170728A (Cannizzo et al.
GCN Circ. 21367), from 84 s to 22.2 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN Circ. 21368).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.89 (+/-0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.22 (+0.32, -0.25). The
best-fitting absorption column is 2.7 (+1.1, -0.4) x 10^21 cm^-2,
consistent with the Galactic value of 2.3 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 3.3 x 10^-11 (5.3 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.7 (+1.1, -0.4) x 10^21 cm^-2
Galactic foreground: 2.3 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.22 (+0.32, -0.25)
If the light curve continues to decay with a power-law decay index of
0.89, 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 9.1 x
10^-14 (1.5 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/00765008.
This circular is an official product of the Swift-XRT team.
|
| GCN 21382 table |
|---|
| GRB_name |
GRB170728A |
| GCN_number |
21382 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21382
SUBJECT: GRB 170728A: LCO observations
DATE: 17/07/29 14:47:33 GMT
FROM: Antonino Cucchiara at UVI
A. Cucchiara, D. Morris (U. of Virgin Islands), and
C. Guidorzi (U. Ferrara), reports on behalf of a larger
collaboration:
"On July 28.38 UT (T_0 +2.1h) we began observing the center
of the field of GRB 170728A (Cannizzo et al. GCN 21367,
Evans et al. GCN 21368) using the Las Cumbres Observatory
1m telescope in Cerro Tololo.
We performed a series of 4x240s observations in R and Ic band
for a total of 16 minutes on sky in each filter at average
airmass of 1.8. Further observations were requested in Sloane
i' filter for a total of 360s.
In the full combined R and I+i' stacks we identified no optical
counterpart within the center of Swift-XRT refined position
(Evans et al. GCN 21368) at the following 3-sigma limits:
R > 18.9 mag
I > 18.4 mag
These magnitudes are calibrated against nearby USNO-B1 sources,
and are not corrected for Galactic extinction."
|
| GCN 21386 table |
|---|
| GRB_name |
GRB170728A |
| GCN_number |
21386 |
| Detection_method |
Swift-UVOT Det |
| ra |
58.8882° |
| decl |
12.1819° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21386
SUBJECT: GRB 170728A: Swift/UVOT Detection
DATE: 17/07/29 21:09:59 GMT
FROM: Sam LaPorte at PSU
GRB 170728A: Swift/UVOT Detection
S. J. Laporte (PSU) 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 170728A
74 s after the BAT trigger (Cannizzo et al., GCN Circ. 21367).
A fading source consistent with the XRT position
(Goad et al. GCN Circ. 21368)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 03:55:33.17 = 58.88819 (deg.)
Dec (J2000) = +12:10:54.7 = 12.18187 (deg.)
with an estimated uncertainty of 0.56 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 70 219 147 19.20+-0.17
white 70 4048 342 19.93+-0.18
v 4264 5808 267 >19.1
b 3655 11916 345 >19.7
u 287 22167 1283 >20.0
w1 6020 21852 1105 >20.1
m2 5814 16112 1082 >20.6
w2 4059 4259 197 >19.6
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.24 in the direction of the burst
(Schlegel et al. 1998).
|
| GCN 21465 table |
|---|
| GRB_name |
GRB170728A |
| GCN_number |
21465 |
| 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
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/.
|