GRB 121028A
GCN Circular 13913
Subject
GRB 121028A: Swift detection of a burst
Date
2012-10-28T05:31:03Z (13 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
R. L. C. Starling (U Leicester), C. Gronwall (PSU),
H. A. Krimm (CRESST/GSFC/USRA), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. H. Siegel (PSU) and T. N. Ukwatta (MSU) report
on behalf of the Swift Team:
At 05:04:31 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 121028A (trigger=536897). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 271.923, -2.285 which is
RA(J2000) = 18h 07m 42s
Dec(J2000) = -02d 17' 04"
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 ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 05:06:41.7 UT, 129.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 271.8995, -2.2936 which
is equivalent to:
RA(J2000) = 18h 07m 35.89s
Dec(J2000) = -02d 17' 36.8"
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This
location is 90 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 (2.48 x
10^21 cm^-2, Kalberla et al. 2005), with an excess column of 4.4
(+4.35/-3.23) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting
134 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 19.2 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 18.0 mag. No
correction has been made for extinction.
Due to the maintenance work at Goddard this weekend (GCN 13905) there
may be a delay in receiving the full dataset, and thus refined
analyses may not be available until late Sunday/early Monday.
Burst Advocate for this burst is R. L. C. Starling (rlcs1 AT star.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.)
GCN Circular 13914
Subject
GRB 121028A: Faulkes Telescope North observations
Date
2012-10-28T08:12:16Z (13 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), A. Gomboc (U. Ljubljana),
on behalf of a large collaboration report:
The 2-m Faulkes Telescope North automatically began observing
GRB 121028A (Starling et al. GCN Circ. 13913) on October 28 2012,
05:07:12 UT corresponding to 161 seconds post burst trigger
with BVRi' filters. Within the XRT error circle we don't see
any uncatalogued object down to the following limits:
Mid time from Exposure Filter Limit
GRB (sec) (s)
-------------------------------------------------------
198 3x10 R > 19
535 10 i' > 18
-------------------------------------------------------
Magnitudes are calibrated against nearby USNOB1 stars.
GCN Circular 13915
Subject
GRB 121028A: MITSuME Okayama Optical upper limits
Date
2012-10-28T13:05:18Z (13 years ago)
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 the MITSuME collaboration:
We observed the field of GRB 121028A (Starling et al., GCNC 13913)
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 2012-10-28 09:15:55 UT (~4.2 h after the burst).
We did not find any new point source within the XRT circle
(Starling et al., GCNC 13913) in all the three bands.
Three sigma upper limits of the OT are listed below. We used
GSC2.3 catalog for flux calibration.
T0+[day] MID-UT T-EXP[sec] g' Rc Ic
------------------------------------------------------
0.21623 10:15:53 6360.0 >19.7 >19.4 >18.7
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 13917
Subject
GRB 121028A: Swift-BAT refined analysis
Date
2012-10-29T00:53:25Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
A. M. Parsons (GSFC), G. Sato (ISAS), M. Stamatikos (OSU),
R. L. C. Starling (U Leicester), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(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 121028A (trigger #536897)
(Starling, et al., GCN Circ. 13913). The BAT ground-calculated position is
RA, Dec = 271.903, -2.298 deg, which is
RA(J2000) = 18h 07m 36.7s
Dec(J2000) = -02d 17' 52.1"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.
The mask-weighted light curve shows a single pulse starting at ~T-0.9 sec,
peaking at ~T+2 sec, and ending ~T+4 sec. T90 (15-350 keV) is 3.8 +- 0.7 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.8 to T+3.8 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.79 +- 0.17. The fluence in the 15-150 keV band is 3.7 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band
is 1.9 +- 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/536897/BA/
GCN Circular 13918
Subject
GRB 121028A: Enhanced Swift-XRT position
Date
2012-10-29T07:15:58Z (13 years ago)
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 2614 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 121028A, 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 = 271.89948, -2.29358 which is equivalent
to:
RA (J2000): 18h 07m 35.87s
Dec (J2000): -02d 17' 36.9"
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.
GCN Circular 13919
Subject
GRB 121028A: Swift-XRT refined Analysis
Date
2012-10-29T07:39:59Z (13 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
K.L. Page (U. Leicester) and R. L. C. Starling (U Leicester) report on
behalf of the Swift-XRT team:
We have analysed 9.4 ks of XRT data for GRB 121028A (Starling et al.
GCN Circ. 13913), from 139 s to 48.8 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 13918).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.87 (+/-0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.63 (+0.26, -0.25). The
best-fitting absorption column is 4.8 (+1.7, -1.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.5 x 10^21 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 5.6 x 10^-11 (7.9 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.8 (+1.7, -1.4) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^21 cm^-2
Excess significance: 2.6 sigma
Photon index: 1.63 (+0.26, -0.25)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00536897.
This circular is an official product of the Swift-XRT team.
GCN Circular 13924
Subject
GRB 121028A: RAPTOR Limits During Gamma-Ray Emitting Interval
Date
2012-10-29T16:05:04Z (13 years ago)
From
James Wren at LANL <jwren@nis.lanl.gov>
J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis,
of Los Alamos National Laboratory report:
The RAPTOR network of robotic optical telescopes made observations of Swift
trigger 536897 (Starling, et al., GCN 13913). The burst location was within
the field of our wide-field monitor located in Maui, HI, which began a 10 s
integration of the location at 05:04:32.5 UT, 0.6 s after the Swift trigger
time and during the gamma-ray emitting interval including the time of peak
emission detected by the BAT (Sakamoto, et al., GCN 13917). We detect no
new object at the location of the refined Swift XRT location (Evans, et al.,
GCN 13918). Our 3-sigma limiting magnitude is 10.0 based on a comparison of
our unfiltered image to the Tycho-2 V-band catalog.
GCN Circular 13927
Subject
GRB 121028A: near-IR observations at Calar Alto
Date
2012-10-29T20:15:14Z (13 years ago)
From
Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>
M. Jelinek, A. J. Castro-Tirado (IAA-CSIC Granada), P. Ferrero (IAC Tenerife),
S. Guziy (Univ. of Nikolaev) and G. Bergond (CAHA Almer�a), on behalf of a larger
collaboration, report:
"Following the detection of GRB 121028A by Swift (Starling et al. GCNC
13913), we triggered the 3.5m CAHA telescope (+ Omega 2000) at the
German-Spanish Calar Alto Observatory. Observations (900s each) were taken
in the YJHK-bands, starting at 18:05 UT (i.e. 13 hr post burst). At the
position of the X-ray afterglow (Evans et al. GCNC 13918), we do not
detect a near-IR countepart in any band, particularly down to H = 20.5."
This message can be quoted.
[GCN OPS NOTE(30oct12): Per author's request, PF was added to the author list.]
GCN Circular 13950
Subject
GRB 121028A: Swift/UVOT Upper Limits
Date
2012-11-05T16:58:22Z (13 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) and R. L. C. Starling (U Leicester) report on
behalf of the Swift/UVOT team.
The Swift/UVOT began settled observations of the field of
GRB 121028A 133s after the BAT trigger (Starling et al.,
GCN Circ. 13913). Data summed from the first and second orbits
do not reveal a source at the enhanced position of the X-ray
afterglow (Evans et al., GCN Circ. 13918).
The 3-sigma upper limits for the finding chart (fc) and
summed exposures are reported below:
FILTER T_start(s) T_stop Exposure Mag/3UL
========================================================
white (fc) 133 283 147 >19.96
white 877 7754 540 >21.07
v 6528 6727 196 >18.94
b 2713 2758 44 >19.10
u 345 595 245 >19.43
u 7143 7343 196 >19.68
uvw1 6938 7138 196 >19.61
uvw2 7761 7961 196 >19.90
=======================================================
The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 1.41 (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric
system described in Breeveld et al. 2011 (AIP Conf. Proc. 1358, 373)