| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
7:06:12 UTC |
GCN_circulars,Swift Det |
| ra |
263.0690° |
Swift |
| decl |
-44.7482° |
Swift |
| pos_error |
4.66e-04° |
Swift |
| T90 |
17.8 s |
Swift |
| T90_start |
7:06:12 UTC |
Swift |
| fluence |
8.30e-07 erg/cm² |
Swift |
| T100 |
17.8 s |
|
| GBM_located |
False |
|
| mjd |
57818.29597222222 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB170306A |
| ra |
263.0833° |
| decl |
-44.7500° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB170306A |
| t_trigger |
7:06:12 UTC |
| ra |
263.0690° |
| decl |
-44.7482° |
| pos_error |
4.66e-04° |
| T90 |
17.8 s |
| fluence |
8.30e-07 erg/cm² |
| GCN 20819 table |
|---|
| GRB_name |
GRB170306A |
| GCN_number |
20819 |
| Detection_method |
Swift Det |
| t_trigger |
7:06:12 UTC |
| ra |
263.0820° |
| decl |
-44.7470° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 20819
SUBJECT: GRB 170306A: Swift detection of a burst
DATE: 17/03/06 07:26:32 GMT
FROM: Jamie A. Kennea at PSU/Swift-XRT
C. B. Markwardt (NASA/GSFC), V. D'Elia (ASDC), J. A. Kennea (PSU),
A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB) and
K. L. Page (U Leicester) report on behalf of the Swift Team:
At 07:06:12 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170306A (trigger=741220). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 263.082, -44.747 which is
RA(J2000) = 17h 32m 20s
Dec(J2000) = -44d 44' 50"
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 ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 07:08:26.0 UT, 133.5 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 263.06892, -44.74808 which
is equivalent to:
RA(J2000) = 17h 32m 16.54s
Dec(J2000) = -44d 44' 53.1"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 33 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 3.82
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 139 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 expected extinction corresponding
to E(B-V) of 0.41.
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.)
|
| GCN 20820 table |
|---|
| GRB_name |
GRB170306A |
| GCN_number |
20820 |
| Detection_method |
Swift Other |
| ra |
263.0698° |
| decl |
-44.7482° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 20820
SUBJECT: GRB 170306A: LCO Cerro Tololo observations
DATE: 17/03/06 09:02:26 GMT
FROM: Cristiano Guidorzi at Ferrara U,Italy
C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc
(U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large
collaboration report:
We observed Swift GRB 170306A (Markwardt et al. GCN 20819) on March 6,
07:26:06 UT (~20 minutes since the GRB trigger time) with the 1-m LCO
unit in Cerro Tololo with SDSS r and i filters. Within the Swift XRT
error circle we detect an uncatalogued source at the following position:
RA(J2000) = 17:32:16.76
Dec(J2000)= -44:44:53.7
with an error radius of 1". We find the following magnitude values as
calibrated against nearby USNOB-1 objects (R2 and I values):
Mid Time Exposure Filter Magnitude (AB)
(min) (s)
-------------------------------------------------------
24 5x60 SDSS-I 18.5 +- 0.2
34 5x60 SDSS-R 19.0 +- 0.2
-------------------------------------------------------
At the moment we cannot make any statement on the temporal behaviour of
the source. The expected Galactic dust extinction is A_r=1~mag, A_i=0.7
mag (from Schlafly et al. 2011). Given the crowded field, we caution
that the source might be unrelated to the GRB.
|
| GCN 20822 table |
|---|
| GRB_name |
GRB170306A |
| GCN_number |
20822 |
| Detection_method |
Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 20822
SUBJECT: GRB 170306A: GROND observations
DATE: 17/03/06 15:17:58 GMT
FROM: Patricia Schady at MPE/Swift
Patricia Schady, Phil Wiseman (both MPE) and Jan Bolmer (ESO, Santiago) report:
We observed the field of GRB 170306A (Swift trigger 741220; Markwardt et al., GCN #20819) simultaneously in grizJHK 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 07:20 UT on 2017-03-06, 14 minutes after the GRB trigger, and they continued for ~2 hours, until the start of astronomical twilight. They were performed at an average seeing of 1.3" and at an average airmass of 1.5.
Within the 3.7" XRT error circle (Markwardt et al., GCN #20819) we detect two uncatalogued sources in addition to the source reported by Guidorzi et al. (GCN #20820). These two newly identified sources have AB magnitudes r~20.0 mag and r~20.3 mag calibrated against GROND zeropoints and uncorrected for the significant Galactic foreground extinction along the line of sight. None of the sources within the XRT error circle show any significant variability during the 2 hours of GROND observations.
We acknowledge the excellent support provided by the Chilean observer at the telescope, and the support astronomer, Angela Hempel, in obtaining these data.
|
| GCN 20823 table |
|---|
| GRB_name |
GRB170306A |
| GCN_number |
20823 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 20823
SUBJECT: GRB 170306A: Swift/UVOT Upper Limits
DATE: 17/03/06 18:52:02 GMT
FROM: Sam Emery at MSSL-UCL
S.W.K. Emery (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 170306A
140 s after the BAT trigger (Markwardt et al., GCN Circ. 20819).
No optical afterglow consistent with the XRT position
(Markwardt et al., GCN Circ. 20819)
and the optical positions
(Guidorzi et al., GCN Circ. 20820; Schady et al., GCN Circ. 20822)
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 140 290 147 >20.0
u_FC 299 548 246 >18.9
white 140 771 186 >20.4
v 629 821 39 >18.1
b 554 747 39 >18.6
u 299 722 265 >19.0
w1 678 870 39 >18.1
m2 653 846 39 >19.0
w2 604 796 39 >18.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.41 in the direction of the burst
(Schlegel et al. 1998).
|
| GCN 20828 table |
|---|
| GRB_name |
GRB170306A |
| GCN_number |
20828 |
| Detection_method |
Swift-XRT Other |
| ra |
263.0690° |
| decl |
-44.7482° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 20828
SUBJECT: GRB 170306A: Swift-XRT refined Analysis
DATE: 17/03/06 21:36:26 GMT
FROM: Phil Evans at U of Leicester
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), 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) and report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:
We have analysed 6.7 ks of XRT data for GRB 170306A, from 119 s to 28.8
ks after the BAT trigger. The data comprise 29 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 refined XRT position is RA,
Dec = 263.0690, -44.7482 which is equivalent to:
RA (J2000): 17 32 16.56
Dec(J2000): -44 44 53.5
with an uncertainty of 3.6 arcsec (radius, 90% confidence).
The light curve can be modelled with an initial power-law decay with an
index of alpha=3.25 (+0.28, -0.21), followed by a break at T+559 s to
an alpha of 0.36 (+0.10, -0.26).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.05 (+0.30, -0.19). The
best-fitting absorption column is 3.98 (+1.64, -0.16) x 10^21 cm^-2,
consistent with the Galactic value of 3.8 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 3.8 x 10^-11 (6.1 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.98 (+1.64, -0.16) x 10^21 cm^-2
Galactic foreground: 3.8 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.05 (+0.30, -0.19)
If the light curve continues to decay with a power-law decay index of
0.36, the count rate at T+24 hours will be 0.011 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x
10^-13 (6.9 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/00741220.
This circular is an official product of the Swift-XRT team.
|
| GCN 20829 table |
|---|
| GRB_name |
GRB170306A |
| GCN_number |
20829 |
| Detection_method |
Swift-BAT Det |
| ra |
263.0870° |
| decl |
-44.7650° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 20829
SUBJECT: GRB 170306A, Swift-BAT refined analysis
DATE: 17/03/07 02:59:37 GMT
FROM: Amy Lien at GSFC
T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
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 170306A (trigger #741220)
(Markwardt et al., GCN Circ. 20819). The BAT ground-calculated position is
RA, Dec = 263.087, -44.765 deg which is
RA(J2000) = 17h 32m 20.9s
Dec(J2000) = -44d 45' 52.5"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 29%.
The mask-weighted light curve shows a pulse that starts at ~T-7 s and ends
at ~T+20 s. In addition, there is a hint of some weak emissions from ~T-100 s
to ~T-80 s. T90 (15-350 keV) is 17.8 +- 6.7 sec (estimated error including systematics).
The time-averaged spectrum from T-7.1 to T+19.7 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.98 +- 0.28. The fluence in the 15-150 keV band is 8.3 +- 1.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+10.93 sec in the 15-150 keV band
is 1.3 +- 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/741220/BA/
|
| GCN 20843 table |
|---|
| GRB_name |
GRB170306A |
| GCN_number |
20843 |
| Detection_method |
Optical |
| ra |
263.0695° |
| decl |
-44.7488° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 20843
SUBJECT: GRB 170306A: GROND afterglow detection
DATE: 17/03/10 13:15:22 GMT
FROM: Patricia Schady at MPE/Swift
Patricia Schady (MPE Garching) reports:
Following on from the GROND (Greiner et al. 2008, PASP 120, 405)
observations of GRB 170306A on the 2017-03-06 (Schady et al., GCN #20819),
I re-observed the field simultaneously in g'r'i'z'JHK with GROND at on
2017-03-10, 4 days after the GRB trigger. Observations were performed at
an average seeing of 1.4" and at an average airmass of 1.7.
One of the three sources detected with GROND (Schady et al., GCN #20819)
within the refined XRT error circle (DAvanzo et al., GCN #20828) is no
longer seen in the latest GROND observations down to the following 3 sigma
limiting magnitudes (all in AB system):
g > 22.6 mag
r > 23.5 mag
i > 22.3 mag
z > 22.4 mag
J > 20.4 mag
H > 19.9 mag
K > 18.9 mag
This source is therefore the likely optical/NIR afterglow of GRB 170306A.
The position of the afterglow candidate is
RA (J2000) = 17:32:16.69
Dec (J2000) = -44:44:55.5
with a positional uncertainty of 0.3" in both coordinates.
Based on combined images with 36 min of total integration time in g'r'i'z'
and 30 min in JHK at a mid-time of 09:33 UT on 2017-03-06, the afterglow
candidate had the following preliminary magnitudes (all in AB system):
g' = 21.6 +/- 0.1 mag
r = 20.4 +/- 0.1 mag
i = 20.0 +/- 0.1 mag
z' = 19.9 +/- 0.1 mag
J = 19.1 +/- 0.1 mag
H = 18.4 +/- 0.1 mag
K = 18.5 +/- 0.2 mag
The given magnitudes are derived based on images calibrated against GROND
zero points in the optical and 2MASS field stars in the NIR bands. They
are not corrected for the Galactic foreground extinction corresponding to
a reddening of E_(B-V)= 0.36 in the direction of the burst (Schlafly &
Finkbeiner 2011).
I acknowledge the excellent support provided by the Chilean observer at
the telescope, and the support astronomer, Sam Kim, in obtaining these
data. I also thank David Buckley for some useful email exchanges that in
part led to the second epoch of GROND observations.
|
| GCN 20844 table |
|---|
| GRB_name |
GRB170306A |
| GCN_number |
20844 |
| Detection_method |
Optical |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 20844
SUBJECT: GRB170306A: SALT observations
DATE: 17/03/10 20:05:16 GMT
FROM: Soebur Razzaque at U of Johannesburg
D.A.H. Buckley (SAAO/SALT), A, Martin-Carrillo (U. College Dublin), S. Razzaque (U. Johannesburg) and R. Skelton (SAAO/SALT) report on behalf of a larger collaboration.
We observed the nominal position of GRB 170306A (Markwardt et al. GCN 20819 and Guidorzi et al. GCN 20820) on 2017-03-07 at 01:22:42 UTC using the Southern African Large Telescope (SALT) in Sutherland, South Africa, 18.61 h after the Swift GRB trigger. A 20 sec r'-band image was obtained using SALTICAM just prior to the commencement of attempted low resolution (R ~ 355 at 660 nm) spectroscopy. Two stellar objects at r’ ~ 19 and 20 were seen, with FWHM of 1.7 arcsec, near the GRB position and long slit spectroscopy was attempted of both. Only the brighter one provided a detection, which was noisy and showed no obvious spectral features. Subsequent information provided by P. Schady on possible optical candidates from the first GROND observation (Schady et al. GCN 20822) was used to confirm the identification of the r’ = 20.4 object identified by Schady (GCN 20843) as the optical counterpart. The SALT image shows a very weak detection of this object, barely above the background, with an estimated brightness of r’= 21.4 +/- 0.3, having dimmed approximately one magnitude since detection.
We thank Patricia Schady and Christiano Guidorzi for providing information to assist in the identification of the optical counterpart.
________________________________
This email and all contents are subject to the following disclaimer:
http://disclaimer.uj.ac.za
|