GRB 110921A
GCN Circular 12373
Subject
GRB 110921A: Swift detection of a burst
Date
2011-09-21T14:01:54Z (14 years ago)
From
David Burrows at PSU/Swift <burrows@astro.psu.edu>
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), S. Campana (INAF-OAB),
J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC),
P. A. Evans (U Leicester), C. Guidorzi (U Ferrara),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
O. M. Littlejohns (U Leicester), V. Mangano (INAF-IASFPA),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
P. T. O'Brien (U Leicester), C. Pagani (U Leicester),
K. L. Page (U Leicester), J. L. Racusin (NASA/GSFC),
T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-OAB/IASFPA),
M. H. Siegel (PSU), E. Sonbas (GSFC/USRA/Adiyaman Univ.),
R. L. C. Starling (U Leicester) and B.-B. Zhang (PSU) report on behalf
of the Swift Team:
At 13:51:20 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110921A (trigger=503652). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 294.078, +36.377 which is
RA(J2000) = 19h 36m 19s
Dec(J2000) = +36d 22' 36"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a ragged, single-peaked
structure with a duration of about 10 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~4 sec after the trigger.
The XRT began observing the field at 13:53:22.5 UT, 122.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 294.09838, 36.32882 which is equivalent
to:
RA(J2000) = 19h 36m 23.61s
Dec(J2000) = +36d 19' 43.8"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 182 arcseconds from the BAT onboard position, outside 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 (1.43 x
10^21 cm^-2, Kalberla et al. 2005), with an excess column of 3.1
(+2.28/-1.97) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 125 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 0.14.
Burst Advocate for this burst is W. H. Baumgartner (wayne 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 Circular 12374
Subject
GRB 110921A: MASTER-Net early limit
Date
2011-09-21T15:00:27Z (14 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V.Yurkov, Yu.Sergienko, E.Sinyakov, D.Varda, I.Kudelina
Blagoveschensk Educational State University, Blagoveschensk
K.Ivanov, S.Yazev, N.M.Budnev, E.Konstantinov, V.Lenok, O.Gres,
O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski,
N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov,
D.Zimnukhov, M. Kornilov, A.Sankovich
Sternberg Astronomical Institute, Moscow State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov
Ural State University, Kourovka
MASTER II robotic telescopes (MASTER-Net: http://observ.pereplet.ru)
located in Amur and in Tunka (Siberia) was pointed to the GRB110921A 7
sec after notice time and 53 sec after GRB time at 2011-09-21
13:52:13.432 UT. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (ra=19 36 19 dec=+36 22 48 r=0.050000).
Observations were made in polarizing bands.
The 5-sigma upper limit has been about 17.2 in Amur and 17.5
in Tunka.
Observations and data reduction is continued.
The message may be cited.
GCN Circular 12377
Subject
GRB 110921A : TNT optical counterpart candidate
Date
2011-09-21T16:30:38Z (14 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L.P. Xin, J.Y. Wei, Y. L. Qiu, J. Wang, J.S. Deng,
C. Wu, X. H. Han on behalf of EAFON report:
We began to observe GRB 110921A (Baumgartner et al., GCN 12373)
with Xinglong TNT telescope at 13:59:40 (UT), about 8 min after
the burst. 25 White-band images and a series of R-band data were obtained.
A new source was detected in the combined white band image within
the errorbox of XRT position. The brightness of this new source is estimated
to be about 20.2 mag derived from USNO B1.0 R2mag.
We propose that this source is the candidate of optical
counterpart of GRB 110921A.
More deep observations are needed to confirm this.
This message may be cited.
For more information about Xinglong GRBs Follow-up
observations, please visit the website:
http://www.xinglong-naoc.org:8080/grb/index.html
GCN Circular 12378
Subject
GRB 110921A: MITSuME Akeno Optical Observation
Date
2011-09-21T16:38:54Z (14 years ago)
From
Yoichi Yatsu at Tokyo Tech. <yatsu@hp.phys.titech.ac.jp>
K. Tokoyoda, M. Hayashi, Y. Yatsu, Y. Aoki, K. Kawakami, S. Song,
R. Usui, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME
collaboration:
We observed GRB 110921A (W. H. Baumgartner et al, GCN12373)
with the optical three color (g, Rc, and Ic) CCD camera attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The follow-up observation was started at 13:53:08, ~108 sec after the
BAT trigger.
We did not find optical counterpart in g'-band and R-band
within the enhanced XRT error circle (W. H. Baumgartner et al, GCN12373).
While, in I-band, we detected a very faint OT candidate in the error circle
only in the earliest data-set (T0+108s ~ T0 + 348s).
Further data analysis for the I-band data is now ongoing.
Photometric results are listed below. We used GSC2.3 catalog for
flux calibration.
T0+[s] MID-UT T-EXP[sec] g' Rc Ic
---------------------------------------------------------------------------------
+108 14:07:40 1530 >20.0 >19.5 ---
---------------------------------------------------------------------------------
T0+ : Elapsed time after the burst [sec]
T-EXP: Total Exposure time [sec]
GCN Circular 12379
Subject
GRB 110921A: Enhanced Swift-XRT position
Date
2011-09-21T20:01:29Z (14 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.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 1830 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 110921A, 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 = 294.09821, +36.32864 which is equivalent
to:
RA (J2000): 19h 36m 23.57s
Dec (J2000): +36d 19' 43.1"
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.
GCN Circular 12380
Subject
GRB 110921A: optical observations in Mt. Terskol and Maidanak observatories
Date
2011-09-21T20:40:56Z (14 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Pozanenko (IKI), M. Andreev, A. Sergeev (Terskol Branch of Institute of
Astronomy), M. Ibrahimov (MAO) on behalf of larger GRB follow up
collaboration report:
We observed the field of the Swift GRB 110921A (Baumgartner et al., GCN
12373) with Zeiss-600 telescope of Mt. Terskol observatory and AZT-22
telescope of Maidanak observatory on Sep. 21. Several images were taken in
both observatories in R filter. Within the enhanced XRT error box (Goad et
al., GCN 12379) we do not detect the candidate of optical counterpart of
GRB 110921A (Xin et al., GCN 12377). Preliminary photometry of a combined
image (Zeiss-600) and a single image of AZT-22 is based on the nearby USNO
B1.0 stars:
UT Filter, Exposure, OT, Upper Limit (3 sigma)
Telescope
(mid) (s)
Sep.21 16:50 R 1800 n/d 21.1
Zeiss-600
Sep.21 17:48 R 300 n/d 21.2
AZT-22
Since our photometry is somewhat deeper than photometry of the candidate
(Xin et al., GCN 12377), we could suggest the candidate is a real afterglow
of GRB 110921A.
GCN Circular 12383
Subject
GRB 110921A, Swift-BAT refined analysis
Date
2011-09-22T01:08:38Z (14 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>
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), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(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 110921A (trigger #503652)
(Baumgartner, et al., GCN Circ. 12373). The BAT ground-calculated position is
RA, Dec = 294.094, 36.355 deg which is
RA(J2000) = 19h 36m 22.6s
Dec(J2000) = +36d 21' 19.8"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 15%.
The mask-weighted light curve shows multiple weak peaks. T90 (15-350 keV) was
48.00 +- 22.63 sec (estimated error including systematics).
The time-averaged spectrum from T-31.55 to T+16.45 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.57 +- 0.17. The fluence in the 15-150 keV band is 2.4 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+7.95 sec in the 15-150 keV band
is 0.2 +- 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/503652/BA/
GCN Circular 12384
Subject
GRB 110921A: Swift-XRT refined Analysis
Date
2011-09-22T08:05:33Z (14 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans (U. Leicester) and W. H. Baumgartner (GSFC/UMBC) report on
behalf of the Swift-XRT team:
We have analysed 9.7 ks of XRT data for GRB 110921A (Baumgartner et
al. GCN Circ. 12373), from 134 s to 40.9 ks after the BAT trigger. The
data comprise 47 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Goad et al. (GCN. Circ 12379).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.90 (+/-0.05).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.00 (+0.15, -0.14). The
best-fitting absorption column is 2.0 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.4 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 3.9 x 10^-11 (5.6 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.0 (+0.5, -0.4) x 10^21 cm^-2
Galactic foreground: 1.4 x 10^21 cm^-2
Excess significance: 7.9 sigma
Photon index: 2.00 (+0.15, -0.14)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00503652.
This circular is an official product of the Swift-XRT team.
GCN Circular 12385
Subject
GRB 110921A: TNT astrometry
Date
2011-09-22T10:16:28Z (14 years ago)
From
Dong Xu at Weizmann Inst <dong.dark@gmail.com>
D. Xu (WIS), L.P. Xin, J.Y. Wei (NAOC) report on behalf of a larger
collaboration:
We performed astrometry to the TNT image (Xin et al., GCN 12377),
calibrated with the SDSS field of GRB 110921A (Baumgartner et al., GCN
12373). The optical afterglow is localised at
RA (J2000): 19h 36m 23.478s
Dec (J2000): +36d 19' 43.38"
with an uncertainty of 1.0 arcsec, in the northwestern part of the
enhanced XRT error circle (Goad et al., GCN 12379).
The SDSS field reveals a source at coordinates
RA (J2000): 19h 36m 23.382s
Dec (J2000): +36d 19' 42.03"
with an uncertainty of 1.0 arcsec and at the southwestern edge of the
XRT error circle, which is too faint to be present for the TNT image.
NIR follow-up observation is encouraged.
GCN Circular 12386
Subject
GRB 110921A: Fermi GBM observation
Date
2011-09-22T15:47:15Z (14 years ago)
From
Gerard Fitzpatrick at UCD <gerard.fitzpatrick@ucdconnect.ie>
G. Fitzpatrick (UCD) reports on behalf of the Fermi GBM Team:
"At 13:51:22.57 UT on 21 September 2011, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 110921A (trigger 338305884 / 110921577),
which was detected by the Swift/BAT (Baumgartner et al. 2011, GCN 12373).
The GBM on-ground location is consistent with the Swift position.
The GBM light curve shows a single bright
peak with a duration (T90) of ~37 s (50-300 keV).
The time-averaged spectrum from T0-26 s to T0+9 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.39 +/- 0.12 and
the cutoff energy, parameterized as Epeak, is 139 +/- 32 keV.
The event fluence (10-1000 keV) in this time interval is
(4.2 +/- 0.4)E-06 erg/cm^2. The 1 s peak photon flux measured
starting from T0+0.5 s in the 10-1000 keV band
is 2.9 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 12387
Subject
GRB 110921A: NOT observations
Date
2011-09-22T16:11:30Z (14 years ago)
Edited On
2024-11-07T19:41:32Z (7 months ago)
From
Paul Vreeswijk at U of Iceland <pmv@raunvis.hi.is>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Paul Vreeswijk (U. Iceland), Daniele Malesani, Antonio de Ugarte
Postigo (DARK, NBI), Dong Xu (WIS), Páll Jakobsson, Steve Schulze
(U. Iceland) and Nial Tanvir (U. Leicester) report on behalf of a
larger collaboration:
Using ALFOSC on the Nordic Optical Telescope (NOT) we have obtained
Sloan r'- (3 x 600 s) and z'-band (6 x 300 s) imaging of the field of
GRB 110921A (Baumgartner et al., GCN 12373, Barthelmy et al., GCN
12383), starting on 2011 September 21.925 UT (roughly 8.3 hr after the
burst). The observations were performed through clouds, but under good
seeing conditions (~0.8").
We do not detect the optical afterglow reported by Xin et al. (GCN
12377, see also Xu et al., GCN 12385), or any other object within the
enhanced Swift-XRT error circle (Goad et al., GCN 12379), down to
limiting magnitudes of about r'=23.3 and z'=21.0 (calibrated against
the SDSS catalog).
Just outside the enhanced XRT error circle, at R.A.(J2000)
19:36:23.38, decl.(J2000) 36:19:42.1 (with an uncertainty of 0.23"),
we detect an r'=22.4+-0.2 source, also visible - albeit barely - in
the combined z'-band imaging. This apparent point source is
consistent, both in position and brightness, with the SDSS object
noted by Xu et al. (GCN 12385).
We are grateful for the NOT staff, particularly Fatemeh Sadat Kiaeerad
and Marjaana Lindborg, for obtaining these observations.
GCN Circular 12389
Subject
GRB 110921A: Swift/UVOT Observations
Date
2011-09-23T14:23:26Z (14 years ago)
From
Alice Breeveld at MSSL-UCL <aab@mssl.ucl.ac.uk>
A. A. Breeveld (MSSL-UCL) and W. H. Baumgartner (GSFC/UMBC) report on
behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110921A
126 s after the BAT trigger (Baumgartner et al., GCN Circ. 12373).
A source consistent with the optical position (Xin et al., GCN Circ.
12377 and Xu et al., GCN Circ. 12385) is detected at 3.5 sigma in the
summed white data, but is not seen in any of the other filters, nor in
any of the white exposures individually.
Preliminary magnitudes and 3-sigma upper limits using the UVOT
photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 126 276 147 >21.3
u_FC 284 534 246 >20.6
white 126 1704 411 21.4 �� 0.3
v 614 5307 308 >20.3
b 540 1679 117 >20.7
u 284 1654 343 >20.9
w1 664 1629 117 >21.1
m2 639 1604 117 >19.7
w2 590 1725 132 >20.6
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).
GCN Circular 12410
Subject
GRB 110921A: MITSuME-Akeno Optical photometry
Date
2011-09-30T16:46:34Z (14 years ago)
From
Yoichi Yatsu at Tokyo Tech. <yatsu@hp.phys.titech.ac.jp>
K. Tokoyoda, M. Hayashi, Y. Yatsu, Y. Aoki, K. Kawakami, S. Song,
R. Usui, and N. Kawai (Tokyo Tech) �report on behalf of the MITSuME
collaboration:
As reported in GCN12378 (Tokoyoda et al.), we detected a very faint object
within the XRT error circle of GRB 110921A (W. H. Baumgartner et al, GCN12373)
with the MITSuME-Akeno 50cm telescope.
Here we report the results of aperture photometry.
We started the follow-up observation at 13:53:08 (UT), ~108 sec after the BAT
trigger(W. H. Baumgartner et al, GCN12373). The optical counterpart can be seen
both in R and I band only in the earliest data-set from T0+108s to T0 + 348s.
For zero-point calibration we used GSC2.3 catalog.
The g' magnitudes of the reference stars were estimated based on Sesar
et al. (2006).
For I-band data we could not find any usable catalog data, therefore we
performed a field photometry.
The Photometric results are summarized below.
Filter �T0+[s] �MID-UT �T-EXP[sec] � Mag �Mag_err � LimitMag
-----------------------------------------------------------------------------------
g' � � � �+108 � �13:55:31 � � � �240 � � � �--- � � �--- � � � � � >19.4
Rc � � �+108 � �13:55:31 � � � �240 � � � 18.8 � �0.2 � � � � � ---
Ic � � � �+108 � �13:55:13 � � � �210 � � � 18.8 � �0.3 � � � � � ---
-----------------------------------------------------------------------------------
GCN Circular 12438
Subject
GRB 110921A: optical observations
Date
2011-10-16T01:25:38Z (14 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (SAI MSU), A. Pozanenko (IKI), E. Klunko (ISTP), V. Rumyantsev
(CrAO), N.Pit (CrAO) on behalf of larger GRB follow up collaboration
report:
We observed the field of the Swift GRB 110921A (Baumgartner et al., GCN
12373) with AZT-33IK telescope of Sayan observatory (Mondy) on Sep. 21
between (UT) 14:36:31 -- 16:05:00 and AZT-11 telescope of CrAO on Sep. 21
between (UT) 17:38:46 -- 19:00:15. In a combined image of a few first frames
taken with AZT-33IK we detected a faint source which coincides with the
optical counterpart of GRB 110921A (Xin et al., GCN 12377; Xu et al., GCN
12385). A photometry is based on the star USNO B1.0 1263-0338839 (19 36
21.52 +36 19 56.2) assuming R=16.13
T0+, Filter, Exposure, OT, UL(3 sigma), Telescope
(mid, d) (s)
0.03934 R 850 22.08 +/- 0.18 22.3 AZT-33IK
0.07558 R 1920 n/d 22.5 AZT-33IK
0.18620 R 4860 n/d 21.3 AZT-11
In a combined image of a total exposure of 3030 s taken with AZT-33IK
telescope we clearly detected the SDSS object noted by Xu et al. (GCN 12385)
and Vreeswijk et al. (GCN 12387). The photometry of the SDSS object against
the above calibration star is R=22.8 +/- 0.3.
GCN Circular 12617
Subject
GRB 110921A: optical observations in Maidanak observatory
Date
2011-12-04T20:50:27Z (14 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (SAI MSU), M. Ibrahimov (UBAI), A. Pozanenko (IKI) report on
behalf of larger GRB follow-up collaboration:
We update results of Maidanak observations preliminary reported in GCN
12380.
We observed the field of the Swift GRB 110921A (Baumgartner et al., GCN
12373) with AZT-22 telescope of Maidanak observatory starting Sep. 21 (UT)
17:45:30. Several images in R-filter of 300 s exposure were taken under
moderate seeing (FWHM ~ 1.7"). We detect a source in coordinates (J2000) 19
36 23.363 +36 19 43.02 with uncertainty of 0.2" and brightness of R = 22.0
+/- 0.15. This source is rather consistent both in position and brightness,
with the SDSS object (Xu et al. GCN 12385; Vreeswijk et al. GCN 12387).
So we do not detect afterglow reported by (Xu et al. GCN 12385; Breeveld et
al. GCN 12389; Tokoyoda et al. GCN 12410; Volnova et al. GCN 12438).
Tstart UT, T0+, Filter, Exposure, OT, Upper Limit (3 sigma)
(mid, d) (s)
17:45:30 0.17895 R 8*300 n/d 22.5