GRB 120911A
GCN Circular 13744
Subject
GRB 120911A: Swift detection of a burst
Date
2012-09-11T07:34:19Z (13 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
J. K. Cannizzo (NASA/UMBC), V. D'Elia (ASDC),
P. A. Evans (U Leicester), C. Guidorzi (U Ferrara),
C. B. Markwardt (NASA/GSFC), A. Maselli (INAF-IASFPA),
K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. H. Siegel (PSU) and E. Troja (NASA/GSFC/ORAU) report on behalf of
the Swift Team:
At 07:08:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120911A (trigger=533268). Swift could not immediately slew
due to the Earth limb constraint. The BAT on-board calculated location is
RA, Dec 357.961, +63.099 which is
RA(J2000) = 23h 51m 51s
Dec(J2000) = +63d 05' 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 at least 30 sec. The peak count rate
was ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+51.6
minutes. There will be no XRT or UVOT data until this time.
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 Circular 13745
Subject
GRB 120911A: ROTSE-III Optical Limits
Date
2012-09-11T07:45:30Z (13 years ago)
From
Wiphu Rujopakarn at U AZ/Steward <rujopakarn@gmail.com>
W. Rujopakarn (Steward), T. Guver (Sabanci U), report on behalf of the
ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB
120911A (Swift trigger 533268; Cannizzo et al., GCN 13744), producing
images beginning 9.2 s after the GCN notice time. An automated
response took the first image at 07:09:04.2 UT, 30.4 s after the
burst, under fair conditions. We took 10 5-sec, 10 20-sec and 40
60-sec exposures. These unfiltered images are calibrated relative to
USNO A2.0 (R). Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma Swift/BAT error circle; however, we are limited as the field
is somewhat crowded. Individual images have limiting magnitudes
ranging from 15.5-16.6; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
07:09:04.2 07:09:09.2 5 15.5 30.4 N
07:09:04.2 07:10:46.4 50 16.9 30.4 Y
GCN Circular 13746
Subject
GRB 120911A: Swift-XRT observations
Date
2012-09-11T09:07:47Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.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 120911A at 08:04:07.0 UT,
3333.2 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 357.98152,
63.09831 which is equivalent to:
RA(J2000) = 23h 51m 55.56s
Dec(J2000) = +63d 05' 53.9"
with an uncertainty of 4.4 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. 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 consistent with the Galactic value of 6.66
x 10^21 cm^-2 (Kalberla et al. 2005).
GCN Circular 13747
Subject
GRB 120911A: Faulkes Telescope North observations
Date
2012-09-11T12:00:22Z (13 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), A. Gomboc (U. Ljubljana),
F. Virgili (LJMU) on behalf of a large collaboration report:
The 2-m Faulkes Telescope North automatically began observing
GRB 120911A (Cannizzo et al. GCN Circ. 13744) on September 11 2012,
08:17:24 UT corresponding to ~70 minutes post burst trigger
with BVRi' filters. Within the XRT error circle (Campana et al.
GCN Circ. 13746), we don't see any uncatalogued object down
to the following limits:
Mid time from Exposure Filter Limit
GRB (hr) (s)
----------------------------------------------------------
1.37 240 R > 20.9
1.45 220 i' > 21.2
----------------------------------------------------------
We note the presence of a faint, uncatalogued object
in the i' band, lying at 5.8" from the XRT centroid, with
a magnitude of i=21.0 +- 0.2 (calibrated against USNOB1 nearby
stars) at the following position:
RA(J2000) = 23:51:56.06
Dec(J2000)= +63:05:49.2
with an error of 0.6". Presently we cannot make any statement
about its temporal behaviour.
GCN Circular 13748
Subject
GRB 120911A: Enhanced Swift-XRT position
Date
2012-09-11T12:16:14Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.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 2099 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 120911A, 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 = 357.97897, +63.09874 which is equivalent
to:
RA (J2000): 23h 51m 54.95s
Dec (J2000): +63d 05' 55.5"
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.
GCN Circular 13749
Subject
GRB 120911A: Swift-BAT refined analysis
Date
2012-09-11T13:18:13Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. K. Cannizzo (NASA/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-239 to T+863 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120911A (trigger #533268)
(Cannizzo, et al., GCN Circ. 13744). The BAT ground-calculated position is
RA, Dec = 357.966, 63.090 deg, which is
RA(J2000) = 23h 51m 51.9s
Dec(J2000) = +63d 05' 25.6"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 23%.
The mask-weighted light curve shows two barely overlapping peaks starting
at ~T-4 sec, peaking at ~T+1 and ~T+17 sec, and ending at ~T+50 sec.
T90 (15-350 keV) is 17.8 +- 3.9 sec (estimated error including systematics).
The time-averaged spectrum from T-1.84 to T+24.10 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.71 +- 0.16. 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-0.30 sec in the 15-150 keV band
is 2.7 +- 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/533268/BA/
GCN Circular 13750
Subject
GRB 120911A: Swift-XRT refined Analysis
Date
2012-09-11T16:15:12Z (13 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
K.L. Page (U. Leicester) and J. K. Cannizzo (NASA/UMBC) report on
behalf of the Swift-XRT team:
We have analysed 7.2 ks of XRT data for GRB 120911A (Cannizzo et al.
GCN Circ. 13744), from 3.3 ks to 17.3 ks after the BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Beardmore et al. (GCN. Circ
13748).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.31 (+0.22, -0.21).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.0 (+/-0.4). The
best-fitting absorption column is 8.4 (+3.4, -1.8) x 10^21 cm^-2,
consistent with the Galactic value of 6.7 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 5.4 x 10^-11 (1.0 x
10^-10) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 8.4 (+3.4, -1.8) x 10^21 cm^-2
Galactic foreground: 6.7 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.0 (+/-0.4)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00533268.
This circular is an official product of the Swift-XRT team.
GCN Circular 13751
Subject
GRB 120911A: Swift/UVOT Upper Limits
Date
2012-09-11T18:48:50Z (13 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (MSSL-UCL) 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 120911A
3323 s after the BAT trigger (Cannizzo et al., GCN Circ. 13744).
No optical afterglow consistent with the XRT position (Beardmore et al.
GCN Circ. 13748) 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 3323 3473 147 >20.5
white 3323 11009 1229 >21.6
v 3479 15918 1278 >19.9
b 4300 10097 1160 >21.5
u 4095 5730 393 >20.4
w1 3890 5526 393 >20.0
m2 3684 5320 393 >21.1
w2 4710 11585 757 >20.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.12 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 13752
Subject
GRB 120911A: Fermi/LAT upper limit
Date
2012-09-11T21:05:23Z (13 years ago)
From
Weikang Zheng at U.of Michigan <zwk@umich.edu>
Weikang Zheng and Carl Akerlof (Umich), report on behalf of the ROTSE
collaboration:
We analyzed Fermi/LAT data of GRB 120911A (Cannizzo et al., GCN 13744)
as a follow-up of routine search in Swift trigger catalogs in our LAT
data processing pipeline using both the matched filter technique
(Akerlof et al. 2010, ApJ, 725, L15; 2011 ApJ, 726, 22; 2012,
arXiv:1205.3066; Zheng et al. 2012, ApJ 745,72; ApJ, 756, 64)
and likelihood method. We do NOT detect high energy photon emission
from both methods.
A standard data selection method is applied when extracting the LAT
photon data with energy E > 100 MeV, and a duration of T0 - T0+47.5s
after the trigger. A zenith angle cut of <105 degree is applied to
all photons.
The burst location of GRB 120911A was only ~14 degrees from the
LAT boresight, almost in the center of the LAT field of view, and
the zenith angle was about 40 degrees at trigger time.
Using the likelihood method, we estimated the upper limit in LAT energy
range (0.1 - 10 GeV) is 1.1e-05 (photons cm^-2 s^-1) by assuming a
spectral index of -2.2.
The pipeline result of GRB 120911A is given in the following link:
http://www.rotse.net/LAT/SwiftTriggers/369040116/
GCN Circular 13753
Subject
GRB120911A: MITSuME Okayama Optical upper limits
Date
2012-09-12T06:18:19Z (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 120911A (Cannizzo et al., GCNC 13744)
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 2012-09-11 13:46:32 UT, (~6.6 h after the burst).
We did not find any new point source within the enhanced XRT circle
(Beardmore et al., GCNC 13748) 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
------------------------------------------------------
0.31808 14:46:35 5940.0 >20.6 >19.8 >19.2
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 13754
Subject
GRB 120911A: Fermi GBM observation
Date
2012-09-12T07:02:43Z (13 years ago)
From
David Gruber at MPE <dgruber@mpe.mpg.de>
David Gruber (MPE) reports on behalf of the Fermi GBM Team:
"At 07:08:33.99 UT on 11 September 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120911A (trigger 369040116 / 120911298).
which was also detected by the Swift/BAT (Cannizzo et al. 2012, GCN 13744).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 11 degrees.
The GBM light curve consists of two pulses
with a duration (T90) of about 22 s (50-300 keV).
The time-averaged spectrum from T0-4.6 s to T0+22.0 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.36 +/- 0.26 and
the cutoff energy, parameterized as Epeak, is 64.2 +/- 5.1 keV
The event fluence (10-1000 keV) in this time interval is
(2.34 +/- 0.04)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.38 s in the 10-1000 keV band
is 4.31 +/- 0.27 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 13759
Subject
GRB 120911A: optical upper limit ISON-NM
Date
2012-09-13T07:13:47Z (13 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
L. Elenin (KIAM), A. Volnova (SAI MSU), I. Molotov (KIAM), A. Pozanenko
(IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 120911A (Cannizzo et al., GCN
13744) with 0.45-m telescope of ISON-NM observatory starting on Sep. 11
(UT) 07:10:42, i.e ~130 s after burst trigger. We took several unfiltered
images of 30 s and 60 s exposures. Within enhanced XRT afterglow position
(Beardmore et al., GCN 13748) we do not detect any new object. A
preliminary photometry of single and co-added frames is based on the
USNO-B1.0 (R2) nearby stars is following:
T0+, Exposure, OT, UL (3 sigma)
mid, d (s)
0.0017 30 n/d 18.4
0.0028 5x30 n/d 19.1
0.0175 60x30 n/d 20.2
0.0590 30x120 n/d 20.6
GCN Circular 13760
Subject
GRB 120911A: optical upper limit CrAO
Date
2012-09-13T07:18:31Z (13 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev, N.Pit' (CrAO), A. Pozanenko (IKI) report on behalf of larger
GRB follow-up collaboration:
We observed the field of the Swift GRB 120911A (Cannizzo et al., GCN
13744) with AZT-11 telescope of CrAO observatory starting on Sep. 11 (UT)
21:10:38. We took several images in R-filter of 180 s exposure. Within
enhanced XRT afterglow position (Beardmore et al., GCN 13748) we do not
detect any new object. A preliminary photometry of co-added frame is
based on the USNO-B1.0 (R2) nearby stars is following:
T0+, Filter Exposure, OT, UL (3 sigma)
mid, d (s)
0.6130 R 20x180 n/d 20.9