GRB 121125A
GCN Circular 13993
Subject
GRB 121125A: Swift detection of a burst with optical counterpart
Date
2012-11-25T08:43:43Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
B. N. Barlow (PSU), S. D. Barthelmy (GSFC), D. Grupe (PSU),
E. A. Helder (PSU) and C. J. Mountford (U Leicester) report on behalf
of the Swift Team:
At 08:32:27 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 121125A (trigger=539563). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 228.520, +55.322 which is
RA(J2000) = 15h 14m 05s
Dec(J2000) = +55d 19' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multiple-peaked
structure with a duration of about 70 sec. The peak count rate
was ~4600 counts/sec (15-350 keV), at ~34 sec after the trigger.
The XRT began observing the field at 08:33:34.1 UT, 66.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 228.52496, 55.31330 which
is equivalent to:
RA(J2000) = 15h 14m 05.99s
Dec(J2000) = +55d 18' 47.9"
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This
location is 32 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 in excess of the Galactic value (1.27 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.7
(+2.20/-1.89) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 4.27e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 75 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 15:14:06.54 = 228.52724
DEC(J2000) = +55:18:48.0 = 55.31332
with a 90%-confidence error radius of about 0.74 arc sec. This position is 1.2
arc sec. from the center of the XRT error circle. The estimated magnitude is
16.19 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.01.
Burst Advocate for this burst is B. N. Barlow (bnb2 AT psu.edu).
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 13994
Subject
GRB 121125A: MASTER-NET optical observations
Date
2012-11-25T09:52:04Z (13 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina,
N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, D.Denisenko,
A.Sankovich
Sternberg Astronomical Institute, Moscow State University
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University
V.Krushinski, I.Zalozhnih, A. Popov
Ural Federal University, Kourovka
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in Blagoveschensk was pointed to the GRB121125.36 44 sec after
GRB time at 2012-11-25 08:33:11.383 UT. On our first (10s exposure) set we
haven`t found optica
l transient within SWIFT error-box (Barlow et al., GCN Circ 13993).
Unfortunately notice alert have come immodiatly after sunset when
telescope prepearing
calibration images.
So 5-sigma upper limit of the first images has been about 13.8 mag that
is not very good.
We see OT (Barlow et al., GCN Circ 13993) on UVOT position on the next
images with 14.5 mag limit (UT_start = 2012-11-25 08:34:34, 127
s after trigger time, exp_time = 30s).
We note that there is 16.5 mag star 9 arcsec from UVOT OT coordinates.
The observations is continuated.
The message may be cited.
GCN Circular 13995
Subject
GRB 121125A: LOAO Observation
Date
2012-11-25T16:47:57Z (13 years ago)
From
Myungshin Im at Seoul Nat U <mim@astro.snu.ac.kr>
M. Im (CEOU/SNU) and Y. Urata (NCU) on behalf of EAFON.
We observed the field of GRB 121125A
(Barlow et al., GCN 13993) in B and R filters using
the 1-m telescope at Mt. Lemmon observatory in Arizona, US.
The observation started at 2012-11-25 12:24:27 UT,
or about 3.87 hours after the BAT alert, and continued for
about 30 min. We identify an object in stacked images of
both B and R at
RA=15:14:06.586, Dec=55:18:47.95 with rms error of 0.6".
This is consistent with the UVOT coordinate of
the afterglow candidate reported in Barlow et al.
The object has R-band magnitude of R = 19.29 +- 0.14 mag,
calibrated against R2 magnitude (16.13 mag) of a USNO-B1 star
at RA=15:14:07.14, Dec=+55:18:40.30. Combined with the result
from Yurkov et al. (GCN 13994) and Barlow et al., our result
reveals a fading behavior of the object, thus we identify
the object to be the afterglow of GRB 121125A.
We thank the LOAO operator, Jae-Hyuk Yoon for performing
the observation.
GCN Circular 13996
Subject
GRB 121125A: Swift-BAT refined analysis
Date
2012-11-25T20:28:47Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), B. N. Barlow (PSU), 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 (AGU), 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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 121125A (trigger #539563)
(Barlow, et al., GCN Circ. 12993). The BAT ground-calculated position is
RA, Dec = 228.519, 55.318 deg, which is
RA(J2000) = 15h 14m 04.6s
Dec(J2000) = +55d 19' 03.5"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.
The mask-weighted light curve shows two clusters of overlapping peaks
that start at ~T-7 sec, peaks at ~T+37 sec, and ends at ~T+100 sec.
T90 (15-350 keV) is 52.2 +- 4.6 sec (estimated error including systematics).
The time-averaged spectrum from T-6.31 to T+77.64 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.52 +- 0.06. The fluence in the 15-150 keV band is 4.7 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+36.56 sec in the 15-150 keV band
is 2.9 +- 0.2 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/539563/BA/
GCN Circular 13997
Subject
GRB 121125A: Fermi GBM Observation
Date
2012-11-25T21:08:30Z (13 years ago)
From
Sinead McGlynn at Excellence Cluster/TUM <smcglynn@tum.de>
Sinead McGlynn (MPE/TUM)
reports on behalf of the Fermi GBM Team:
"At 08:32:29.63 UT on 25 Nov 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 121125A (trigger 375525152/121125356), which was also detected by the Swift/BAT
(Barthelmy et al. 2012, GCN 13996). The GBM on-ground location is consistent with the Swift/UVOT afterglow candidate position (Barlow et al. 2012, GCN 13993).
The on-ground calculated location, using the GBM trigger
data, is RA = 229.30, DEC = +54.14 (J2000 degrees,
equivalent to 15h 17m 12s, 54d 08' 24"), with an uncertainty
of 2.22 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 37 degrees.
The GBM light curve shows/consists of several pulses
with a duration (T90) of about 50 s (50-300 keV).
The time-averaged spectrum from T0-11.3 s to T0+49.1 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.38 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 196 +/- 26 keV.
The event fluence (10-1000 keV) in this time interval is
(9.5 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+32 s in the 10-1000 keV band
is 4.2 +/- 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 13998
Subject
GRB 121125A: Enhanced Swift-XRT position
Date
2012-11-25T22:06:30Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.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 4397 s of XRT Photon Counting mode data and 10 UVOT
images for GRB 121125A, 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 = 228.52806, +55.31335 which is equivalent
to:
RA (J2000): 15h 14m 6.73s
Dec (J2000): +55d 18' 48.1"
with an uncertainty of 1.5 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 13999
Subject
GRB 121125A: Swift-XRT refined Analysis
Date
2012-11-25T23:43:03Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), M.C. Stroh (PSU), D.N.
Burrows (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester), O.M.
Littlejohns (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo
(INAF-OAB) and B.N. Barlow report on behalf of the Swift-XRT team:
We have analysed 9.6 ks of XRT data for GRB 121125A (Barlow et al. GCN
Circ. 13993), from 73 s to 23.5 ks after the BAT trigger. The data
comprise 196 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 13998).
The late-time light curve (from T0+4.0 ks) can be modelled with a
power-law decay with a decay index of alpha=1.28 (+/-0.08).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.02 (+0.10, -0.09). The
best-fitting absorption column is 1.49 (+0.23, -0.22) x 10^21 cm^-2,
in excess of the Galactic value of 1.3 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 2.14 (+0.13, -0.12)
and a best-fitting absorption column of 1.02 (+0.28, -0.26) x 10^21
cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.4 x 10^-11 (4.6 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.02 (+0.28, -0.26) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 5.6 sigma
Photon index: 2.14 (+0.13, -0.12)
If the light curve continues to decay with a power-law decay index of
1.28, the count rate at T+24 hours will be 0.013 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x
10^-13 (5.7 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/00539563.
This circular is an official product of the Swift-XRT team.
GCN Circular 14002
Subject
GRB 121125A: Swift/UVOT Detection
Date
2012-11-26T22:17:56Z (13 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and B. N. Barlow (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 121125A
75 s after the BAT trigger (Barlow et al., GCN Circ. 13993).
A source consistent with the XRT position
(Goad et al., GCN Circ. 13998) is detected in the initial UVOT exposures.
The refined UVOT position is:
RA (J2000) = 15:14:06.58 = 228.52740 (deg.)
Dec (J2000) = +55:18:48.0 = 55.31332 (deg.)
with an estimated uncertainty of 0.50 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 75 225 147 16.35 +/- 0.03
v 4693 4892 197 19.11 +/- 0.19
b 4076 4276 197 19.31 +/- 0.13
u 288 423 134 16.21 +/- 0.04
w1 5103 5302 197 20.06 +/- 0.32
m2 4897 11750 1082 >21.9
w2 4488 6123 393 >21.6
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 14020
Subject
GRB 121125A: optical upper limit
Date
2012-11-29T17:52:31Z (13 years ago)
From
Alina Volnova at SAI MSU <alinusss@gmail.com>
A. Volnova (SAI MSU, IKI), D. Varda (ISON), E. Sinyakov (ISON), I. Molotov
(KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of GRB 121125A (Barlow et al., GCN 13993) with ORI-25
telescope of ISON-Blagoveshensk observatory starting on Nov.25 (UT)
09:05:39. We took several unfiltered images. We do not detect the OT
(Barlow et al., GCN 13993; Yurkov et al., GCN 13994; Im et al., GCN 13995)
in any combined images. A photometry of stacked image is based on nearby
USNO-B1.0 stars (R2):
T_start T0+, Filter, exposure, UL (3 sigma)
(UT) mid (d) (s)
08:58:19 0.03078 none 52 x 40 15.6