GRB 081203A
GCN Circular 8695
Subject
GRB081203A: BTA observation
Date
2008-12-22T12:38:47Z (17 years ago)
From
Vladimir Sokolov at SAO RAS <sokolov@sao.ru>
T. Fatkhullin, A. Moskvitin (SAO RAS, Russia), A. Posanenko (IKI RAS,
Russia), E. Sonbas (SAO RAS,University of Cukurova, Turkey ),
A. Volnova (SAI MSU), V. Rumyantsev (CrAO), V. Kouprianov (GAO RAS),
V. Sokolov (SAO RAS) and A.J. Castro-Tirado ((IAA-CSIC Granada, Spain)
on behalf of a larger collaboration report:
We observed the field of the GRB081203A (A. M. Parsons et al., GCN #8595)
in the Rc-band with the 6-m telescope of the SAO RAS in Caucasus. In total 15
3-min exposures were obtained starting from 01:42 7 Dec. 2008 UT (T-T_0 =
3.49 days). We clearly detected an object at the position of the UVOT
optical transient (M. De Pasquale and A. Parsons, GCN #8603).
Calibration based on the SDSS stars yields the brightness of the OT as
R = 23.94 +/- 0.13 (errors are statistical only). At the 3.2 +/- 0.2
arcsec to the South-West from the OT position we also detect an extended
object with R = 22.74 +/- 0.07. For redshift of z=2.05 (N.P.M Kuin et al,
astro-ph/0812.2943) it corresponds to ~26 kpc in projection (H0=71,
Omega_M=0.3, Omega_L=0.7). It is unlikely that this object is a host
galaxy of the GRB081203A but redshift measurements are needed for certainty.
Further observations are planned.
Our finding chart can be dowloaded from
ftp://ftp.sao.ru/pub/grb/GRB081203A/GRB081203A_OT.jpg
This message can be cited
GCN Circular 8645
Subject
GRB 081203A: optical observations
Date
2008-12-10T02:07:24Z (17 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev, K. Antonyuk (CrAO), M. Andreev(Terskol Branch of Institute
of Astronomy), A. Pozanenko (IKI) on behalf of larger GRB follow up
collaboration report:
We observed the field of GRB 081203 (Parsons et al, GCN 8595) with the
AZT-11 telescope of CrAO observatory starting Dec. 03 (UT) 15:44:29
under good weather conditions and seeing of about ~2 arcsec. Several
exposures were obtained in VRI bands up to 17:13:56 and then between
Dec. 04 (UT) 01:19:13 - 02:47:51.
Coordinates of the afterglow are RA(J2000)= 15:32:07.58 Dec(J2000)=
+63:31:14.8 with uncertainty of 0.2 arcsec which is compatible with the
coordinates of the afterglow (Parsons et al, GCN 8595).
Preliminary photometry based on SDSS star J153200.06+633229.9
(RA(J2000)=15:32:00.01 Dec(J2000)=+63:32:30.4) assuming V=17.28 R=16.85
I=16.46 is following
T0+ Filter Exp. mag.
s s
6528 V 180 16.84 +/-0.02
6712 R 180 16.63 +/-0.02
6896 I 180 16.22 +/-0.02
11524 V 180 17.68 +/-0.05
11708 R 180 17.53 +/-0.03
11892 I 180 17.15 +/-0.04
41196 R 3x180 20.27 +/-0.15
46144 R 3x180 20.20 +/-0.14
While light curves in a time interval 6500 - 12000 s after burst onset in
R and I bands look similar with a power law decay index of about 0.66, the
power law decay index in V-band is ~0.59 and one can suggest a spectral
variability of the afterglow. Also we observed steep decay between 12000 -
46000 s with a power law index of about 1.9.
GCN Circular 8632
Subject
GRB081203A: Ashra-1 observation of early optical and VHE-neutrino emission
Date
2008-12-07T16:54:46Z (17 years ago)
From
Makoto Sasaki at ICRR/U.Tokyo <sasakim@icrr.u-tokyo.ac.jp>
Y.Aita, Y.Asaoka, T.Chonan, Y.Higashi, K.Noda, and M.Sasaki
(ICRR,Univ.Tokyo), Y.Morimoto, S.Ogawa (Toho Univ.), J.Learned
(Univ.Hawaii Manoa), R.Fox (Univ.Hawaii Hilo) report on behalf of the
Ashra-1 collaboration:
We have searched for optical and VHE-neutrino emission in the field of
GRB081203A (A. M. Persons et al., GCN Circ. 8595) around the
BAT-triggered GRB time (T0) with one of the light collector units in
the Ashra-1 detector (http://www.icrr.u-tokyo.ac.jp/~ashra) on Mauna
Loa on Hawaii Island (latitude = 19.5412 deg. N, longitude =155.5676
deg. W, altitude =3330m).
The Ashra-1 light collector unit has the achieved resolution of a few
arcmin, viewing 42 degree circle region of which center is located at
Alt = 11.7 deg, Azi = 22.1 deg. The sensitive region of wavelength is
similar with the B-band.
We quickly analyzed 83 images covering the field of GRB081203A every
7.2s with 6s exposure time respectively during the observation between
T0-300s and T0+300s. We detected no new optical object within the PSF
resolution around the GRB081203A determined by Swift-UVOT (M. De
Pasquale et al.,GCN Circ. 8603).
As a result of our preliminary analysis, the following 3-sigma
limiting magnitudes are derived:
----------------------------------------------------------------------
Starting&Ending Exp.Time, 3-sigma Limit. Mag.
----------------------------------------------------------------------
-297.7 -291.7 11.9
-290.7 -284.7 11.9
. . .
. . .
-1.7 4.3 11.9
5.3 11.3 11.8
. . .
. . .
287.3 293.3 11.9
294.3 300.3 11.9
----------------------------------------------------------------------
The limiting magnitudes were estimated in comparison with stars in
Tycho-2 Catalog to be distributed between 11.7 and 12.0 as above
partly listed.
Adding that we have searched for VHE-neutrino emission with the
primary neutrino energy above 10^16eV by detecting Cherenkov lights
from tau-decay induced air-showers. VHE neutrinos are expected to be
produced at the GRB behind Mauna Kea and converted into tau leptons in
the mountain rock. The GRB position was passed through our triggering
region viewing onto the face of Mauna Kea from 11:07UT to 11:49UT
(2.83 hours to 2.13 hours before the GRB). We have no signal come out
of the mountain. The limiting flux is now under analysis.
Figures of limiting optical magnitudes vs time comparing with other
measurements and more details on the VHE neutrino observation can be
found at: http://www.icrr.u-tokyo.ac.jp/~ashra/GRB081203A.
This message may be cited.
////////////////////////////////////////////////////////////////
SASAKI Makoto
ICRR, University of Tokyo
5-1-5 Kashiwa-no-ha Kashiwa 277-8582
tel/fax +81-4-7136-3143
////////////////////////////////////////////////////////////////
GCN Circular 8629
Subject
GRB081203A: Optical observations at Ishigaki
Date
2008-12-06T13:25:53Z (17 years ago)
From
Mizuki Isogai at NAOJ <mizuki.isogai@nao.ac.jp>
M. Isogai (IAO, NAOJ) and N. Kawai (Tokyo Tech) report with support
of MITuME collaboration:
We observed the field of GRB 081203A(Parsons, et al., GCN Circ. 8595)
with the optical 3-color imager attached to the 105cm Murikabushi
Telescope at Ishigakizima Astronomical Observatory in Japan from
UT 19:52, 5.9 hours after the trigger.
In the co-added images of Ic, Rc, and g' bands, we detected a fading
point source and measured its magnitude. Photometric calibration was
performed using the GSC2.3 catalogs.
The results are following:
MID-MJD MID-UT EXP-T g' Rc Ic
----------------------------------------------------------------------
54803.837345 20:05:46 720.0 18.50+/-0.09
54803.837345 20:05:46 900.0 19.43+/-0.11 18.76+/-0.06
54803.847273 20:20:04 720.0 19.39+/-0.11
54803.848363 20:21:38 900.0 18.83+/-0.06 18.49+/-0.08
54803.859451 20:37:36 900.0 19.57+/-0.11 18.96+/-0.06 18.67+/-0.09
54803.870356 20:53:18 900.0 19.77+/-0.11 18.94+/-0.07 18.72+/-0.10
54803.881257 21:09:00 900.0 19.71+/-0.12 19.04+/-0.07 18.71+/-0.10
GCN Circular 8623
Subject
GRB081203A: Radio upper limit at 15 GHz
Date
2008-12-05T17:33:51Z (17 years ago)
From
Guy Pooley at MRAO, Cambridge, UK <ggp1@cam.ac.uk>
Guy Pooley (MRAO/Cavendish Astrophysics, University of Cambridge) reports:
We used the AMI large array (the rebuilt/upgraded Ryle Telescope)
in the band 14 - 17 GHz to observe the field of the optically
bright GRB 081203A (GCN 8595). There was no detection of the afterglow on
either of two observations. The measured flux densities at the optical
position are:
2008 Nov 04.26 116 +- 300 microJy
2008 Nov 05.24 80 +- 200 microJy
(cf Chandra & Frail, GCN 8613, for an upper limit at 8.46 GHz)
GCN Circular 8619
Subject
GRB081203A: MITSuME optical observation
Date
2008-12-05T11:04:48Z (17 years ago)
From
Michitoshi Yoshida at Okayama Astrophysical Obs <yoshida@oao.nao.ac.jp>
Y. A. Mori, H. Nakajima, T. Shimokawabe, N. Kawai (Tokyo Tech),
D. Kuroda, M. Yoshida, K. Yanagisawa, Y. Shimizu, H. Toda, and
S. Nagayama (OAO, NAOJ) report on behalf of the MITSuME
collaboration:
We performed optical imaging observation of the field of GRB 081203A
(Parsons, et al., GCN Circ. 8595) with the 3-color 50cm MITSuME
Telescopes at Akeno Observatory and Okayama Astrophysical Observatory
from UT 17:50 to UT 20:55, 3.9 hours after the trigger.
In the co-added images of Rc, and g' bands, we detected the optical
afterglow detected with UVOT (Parsons, et al., GCN Circ. 8595).
Photometric calibration was done using the GSC2.3 catalogs.
The results are following:
Akeno:
MID-MJD MID-UT EXP-T g' Rc
----------------------------------------------------------
54803.753779 18:12:54 1620.0 18.50+/-0.24 18.11+/-0.25
----------------------------------------------------------
Okayama:
MID-MJD MID-UT EXP-T g' Rc
----------------------------------------------------------
54803.790960 18:58:59 1500.0 18.87+/-0.26 18.36+/-0.19
54803.811830 19:29:03 1500.0 19.18+/-0.25 17.89+/-0.15
54803.833037 19:59:35 1560.0 19.11+/-0.23 18.49+/-0.24
54803.854522 20:30:31 1560.0 19.63+/-0.32 18.91+/-0.19
----------------------------------------------------------
GCN Circular 8618
Subject
GRB 081203A: Optical observations of Xinglong TNT telescope
Date
2008-12-05T07:57:42Z (17 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
H. Liu, J. Wang, L.P. Xin, Y.L. Qiu, J.Y. Wei, J.Y. Hu,
J.S. Deng, W.K. Zheng and Y. Urata on behalf of EAFON report:
We have observed GRB081203A (Parsons et al., GCN 8595)
with Xinglong TNT telescope from Dec.03th,13:57:11(UT),
6.43 hr after the burst to Dec.03,22:19:37.67 (UT).
A series of R band and V band have been obtained.
The optical afterglow was clearly detected in all the images.
Further observations of GRB081203A were also made with
Xinglong TNT telescope from Dec.04th,21:29:30.409(UT). The
OT was still marginal detected after combined 11*600s images.
we found the afterglow dacayed from R=19.0 at 7.25 hr to
R=21.1 at 24.6 hr. The decay slope index is about 1.59, which is
consistent with the index derived from Volkov et al,(GCN 8604).
Further observations are encouraged.
This message may be cited.
For more information about Xinglong GRBs Follow-up
observations, please visit the website:
http://www.xinglong-naoc.org/grb/
GCN Circular 8617
Subject
GRB 081203A: Skynet/GORT Detections
Date
2008-12-05T01:15:13Z (17 years ago)
From
James Philip West at UNC/Chapel Hill <jpwest@uncg.edu>
J. P. West, K. McLin, T. Brennan, J. Haislip, D. Reichart, L. Cominsky, T.
Graves, G. Spear, K. Ivarsen, J. A. Crain, A. Foster, R. Holmes, A.
LaCluyze, M. Schubel, J. Styblova, A. Trotter, and E. Weaver report:
Skynet observed the localization of GRB 081203A (Parsons et al., GCN 8595)
with the 14" GORT telescope at Hume Observatory in California beginning 122
seconds after the trigger (101 seconds after notification) in RI.
Only five exposures were taken before morning twilight. We detect the
afterglow (Parsons et al., GCN 8595) in all five exposures. Calibrated to
five USNO B1 stars, we find:
mean time
since trigger exposure filter magnitude
(sec) (sec)
134 20 I 12.79 +/- 0.02
235 40 R 12.60 +/- 0.01
345 40 I 11.58 +/- 0.01
476 80 R 12.51 +/- 0.01
625 80 I 12.02 +/- 0.01
[GCN OPS NOTE(05dec08): Per author's request, the "magnutude time" column label
was changed to "magnitude".]
GCN Circular 8615
Subject
GRB081203A: optical observation
Date
2008-12-04T18:32:07Z (17 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy), Ju.
Babina (CrAO), A. Pozanenko (IKI) on behalf of larger GRB follow up
collaboration report:
We observed the field of GRB 081203 (Parsons et al, GCN 8595) with the
Z-600 telescope of Mt. Terskol observatory between (UT) Dec.03 14:29-14:38
(unfiltered exposures of 15 s), Dec.03 14:50 - Dec.04 01:45 (R-band
exposures of 60 s), and starting (UT) Dec.04 15:27.
In mid time Dec.04 (UT) 00:50 the afterglow is detected on combined images
and R=19.5 +/-0.2. In mid time Dec. 04 (UT) 15:32 we do not detect the
afterglow up to R=20.6 (3 sigma). The photometry is still preliminary and
basen on star of SDSS J153155.64+632959.4 (=USNO-B1.0 1534-0214259),
assuming R=14.69.
GCN Circular 8613
Subject
VLA Radio upper limit on GRB 081203A
Date
2008-12-04T18:06:19Z (17 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
Poonam Chandra (RMC) and Dale A. Frail (NRAO) report on
behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to observe the field of view toward
optically bright GRB 081203A (GCN 8595) at a frequency of 8.46 GHz
on 2008 Dec 04.39 UT. The GRB radio afterglow is undetected and
the peak radio flux at the UVOT position (GCN 8595) is 76 � 54 uJy.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 8611
Subject
Konus-Wind observation of GRB 081203A
Date
2008-12-04T16:01:56Z (17 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin,
D. Frederiks, P. Oleynik, D. Svinkin, M. Ulanov,
and T. Cline, on behalf of the Konus-Wind team report:
The long GRB 081203A (Parsons et al., GCN 8595, Ukwatta et al., GCN
8599) was detected by Konus-Wind in the same trigger record as GRB
081203B (Copete et al., GCN 8600, 8602; Golenetskii et al., GCN 8610) at
~T0(KW)+260s.
(T0(KW)=49890.368 s UT (13:51:30.368). Correcting for the propagation
time delay from Wind to Swift of 0.7s, one sees that T0(BAT) corresponds
to T0(KW)+339.9s).
Since this burst occurred after the end of the time history record
(=T0(KW)+229s) we do not have the light curve of this GRB with good time
resolution. Instead we have KW multichannel spectra accumulated until
T0(KW)+490s (that is until T0(BAT)+150s), which were converted to a
3-band light curve with a time resolution of 8.192 s.
The burst light curve shows a weak emission starting at ~T0(BAT)-80s
(=T0(KW)+260s), the main double-peaked pulse starting at ~T0(BAT)-14s
(=T0(KW)+326s) and the decaying tail seen at least until T0(BAT)+134s
(=T0(KW)+474s).
As observed by Konus-Wind the burst
had a fluence of 3.05(-0.89, +1.40)x10^-5 erg/cm2
(in the 20 keV - 3 MeV energy range).
The time-integrated spectrum of the burst
(from T0(BAT)-79s to T0(BAT)+134 s) is well fitted
(in the 20 keV-3 MeV range) by a simple power law model
with index 1.54 +/- 0.08 (chi2 = 65.8/69 dof).
Fitting by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields
alpha = -1.33(-0.20, +0.27)
and Ep = 578(-290, +2398) keV (chi2 = 61.2/68 dof).
The spectrum of the main pulse
(from T0(BAT)-14s to T0(BAT)+52s) is well fitted
(in the 20 keV-3 MeV range) by a power law
with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.29(-0.13, +0.15)
and Ep = 497(-156, +383) keV (chi2 = 66.2/68 dof).
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available
at http://www.ioffe.ru/LEA/GRBs/GRB081203A/
GCN Circular 8609
Subject
GRB081203A: Swift-XRT refined analysis
Date
2008-12-04T08:56:13Z (17 years ago)
From
Valentina La Parola at INAF-IASPA <laparola@ifc.inaf.it>
V. La Parola, B. Sbarufatti, V. Mangano (INAF-IASF Pa), A. Parsons (GSFC)
report on behalf of the Swift XRT team:
We have analysed the first 3 orbits of Swift-XRT data obtained for
GRB 081203A (trigger #336489, Parsons et al., GCN Circ.8595), that includes
550 s of Windowed Timing (WT) and 15.5 ks of Photon Counting (PC) mode data,
respectively, between 87 s and 16 ks after the trigger.
The UVOT-enhanced XRT position was given by Evans et al. in GCN Circ 8598.
The light-curve can be modelled with a broken power-law, with a steep
decay alpha_1=4.32 � 0.16 and a break time at T_b=T0+(150+/-3) s.
After the break the decay flattens to alpha_2=1.175 � 0.015
The spectrum extracted from the WT data has an exposure of 558 s. It can be
modelled with an absorbed power-law, with Gamma =1.97 � 0.04 and an
intrinsic
NH = (5.5 � 0.8)x10^20 cm-2, in excess to the Galactic value of
1.7x10^20 cm-2.
The observed (unabsorbed) 0.3 -10 keV averaged flux over this time
interval is 8.6x10^-10 (10x10^-10) erg cm-2 s-1.
The spectrum extracted from the PC data in the time interval 0.6-16 ks
(with an
exposure time of 4.7 ks) can be modelled with an absorbed power-law, with
Gamma = 2.1 � 0.08 and an intrinsic column density of NH = (6.0 �
1.7)x10^20 cm-2.
The observed (unabsorbed) 0.3 -10 keV averaged flux over this time
interval is 2.8x10^-11 (3.6x10^-11) erg cm-2 s-1.
Uncertainties are given at 90% confidence.
If the light-curve continues to decay with the present rate, the count
rate 24
(36) hours after the burst is estimated to be 0.02 (0.013) count s-1, which
corresponds to an observed flux of 7x10^-13 (4.5x10^-13) erg cm-2 s-1.
The results of the xrt automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00336489.
This is an official product of the Swift-XRT team.
GCN Circular 8604
Subject
GRB 081203A: optical observations
Date
2008-12-03T23:08:16Z (17 years ago)
From
Igor Volkov at Asro.Inst.Slovak Acad.Sciences <volkov@ta3.sk>
On 2008 December 03 I have monitored the field of GRB 081203A detected by
SWIFT (Parsons, et al., GCN Circ. 8595) with the 0.5m reflector and
ST-10XME CCD camera of Stara Lesna (Slovak Republic) observatory. My
frames confirm the presence of the afterglow close to coordinates (J2000)
RA = 15h 32m 07.6s, Dec = +63d 31m 14.9s (M. De Pasquale and A. Parsons,
GCN Circ. 8603 ). Observations continued from UT 15:24:45 to UT 16:58:45
in Rc photometric system. The object faided from Rc=15.74+/-0.04 to
Rc=17.20+/-0.06 during this time interval. Several BVIc measurements were
also obtained. GSC 4184 1309 served as a comparison star. The reduction of
the data is in progress and will be available on request.
This study was supported by the SAI scholarship.
Igor Volkov, Astronomical Institute of the Slovak Academy of Sciences, 059
60 Tatranska Lomnica, Slovak Republic; e-mail: volkov@ta3.sk
GCN Circular 8603
Subject
Swift UVOT observations of GRB 081203A
Date
2008-12-03T22:06:27Z (17 years ago)
From
Massimiliano de Pasquale at MSSL-UCL <mdp@mssl.ucl.ac.uk>
M. De Pasquale (MSSL/UCL) and A. Parsons (GSFC) reports, on the
behalf of the Swift UVOT team:
Swift UVOT began settled exposures of GRB081203A (trigger 336489,
Parsons et al, GCN circular 8595) 93 s after the burst trigger. A
bright optical transient is detected at the following coordinates:
RA = 15h 32m 07.58s (=233.031580), Dec = +63d 31m 14.9s (=63.520810)
J2000
with an uncertainty of 0.5'' (90% confidence level). This position is
consistent with the XRT refined error circle (Goad et al, GCN circ 8598).
The source is detected in all filters but um2. Below, we show time of
observations, the exposure time and the magnitude and 3 sigma upper
limits for this optical afterglow.
T_start (s) T_stop (s) Exp (s) Mag
wh 93 242 146.2 14.53 +/- 0.01
wh 586 605 19.5 13.91 +/- 0.01
v 636 655 19.5 13.30 +/- 0.03
b 561 580 19.5 13.53 +/- 0.01
u 306 555 246 13.07 +/- 0.01
u 709 728 19.5 13.53 +/- 0.02
uw1 685 704 19.5 14.82 +/- 0.07
um2 660 679 19.5 > 17.57
um2 660 6008 412.6 > 20.1
uw2 611 630 19.5 17.19 +/- 0.25
The nondetection in the um2 filter is consistent with the
redshift z=2.1 derived from grism spectra (Landsman et al, GCN
circ 8601). The detection in the uw2 filter is consistent with
this redshift due to the long-wavelength tail of the uw2
filter response.
The above magnitudes have not been corrected for the Galactic
extinction corresponding to E(B-V) = 0.02 (Schlegel et al 1998)
The photometry is on the UVOT flight system described in Poole
et al (2008, MNRAS, 383,627)
[GCN OPS NOTE(03dec08): Per author's request, the "A" was added to the burst name.]
GCN Circular 8601
Subject
GRB081203A: Swift/UVOT grism redshift
Date
2008-12-03T19:36:15Z (17 years ago)
From
Wayne Landsman at GSFC/SSAI <wayne.b.landsman@nasa.gov>
W. Landsman (NASA/GSFC), M. DePasquale(MSSL), P. Kuin (MSSL), P.
Schady (MSSL), P. Smith (MSSL), and A.Parsons (NASA/GSFC) report
on behalf of the Swift/UVOT team:
The Swift/UVOT obtained a 49s UV grism spectrum of GRB 081203A starting
249 s after the BAT trigger (Parsons et al. GCN.8595). The
spectrum covers the wavelength range from 2000-4900 A. Longward of
2850 A in the
quicklook spectrum there is an approximately flat continuum of
2.5e-14 erg s-1 cm-2 A-1 with a strong absorption at 3850 A. If the
2850 A cutoff is identified with the Lyman edge, and the 3850 A
absorption with Lyman alpha, then the redshift of GRB081203A is
~2.1. Analysis is continuing.
GCN Circular 8600
Subject
GRB 081203A: Burst detection from Swift-BAT slew data
Date
2008-12-03T18:54:02Z (17 years ago)
From
Antonio Copete at Harvard U <acopete@head.cfa.harvard.edu>
A. Copete, J. Grindlay (Harvard)
S. Barthelmy, C. Markwardt, N. Gehrels (NASA/GSFC)
We report the detection of a GRB candidate by the BAT Slew Survey
(BATSS) in the slew that started at 13:52:02 UT. This is 309 sec
before the trigger time for the GRB that followed (A. M. Parsons et
al, GCN 8595), which occurs at a different location and should
hereafter be referred to as GRB 081203B.
The ground-calculated position of GRB 081203A is RA, Dec = 228.789,
+44.427 deg, which is
RA (J2000) = 15h 15m 09s
Dec (J2000) = +44d 25' 36"
with an uncertainty of 3.04 arcmin (90% confidence, including
systematics). The detection was triggered by simultaneous
independent detections of 11.0 sigma and 5.6 sigma from imaging in the
15-50 keV and 50-150 keV energy bands, respectively. The burst mask-
tagged lightcurve shows 2 main peaks, the larger one at T+24sec and
lasting 2sec as the burst enters the BAT FoV, the second one at T
+30sec with a duration of 2sec, and it has largely faded as the
pointing observation that follows begins. The measured T90 = 23.4sec
and T50 = 8.2sec (15-150keV).
Preliminary spectral analysis from T+24.0 to T+50.4 shows a time-
averaged spectrum that is best fit by a simple power law with photon
index of 1.65. The total fluence in the 15-150 keV band is 2.1 x 10^-6
erg/cm2, and the 1-sec peak flux is 3.5 x 10^-7 erg/cm2/sec.
A follow-up Swift ToO observation has been scheduled to begin at 18:26
UT, 4.6 hours after the burst.
GCN Circular 8599
Subject
GRB 081203A: Swift-BAT refined analysis
Date
2008-12-03T18:41:04Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. N. Ukwatta (GWU), 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/UMD), D. M. Palmer (LANL),
A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+482 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 081203A (trigger #336489)
(Parsons, et al., GCN Circ. 8595). The BAT ground-calculated position is
RA, Dec = 233.071, 63.514 deg, which is
RA(J2000) = 15h 32m 16.9s
Dec(J2000) = +63d 30' 50.2"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 57%.
The mask-weighted light curve shows two overlapping peaks. The first starts
at ~T-70 sec and peaks at ~T+10 sec. The second peaks at ~T+32 sec and
ends at ~T+400 sec. T90 (15-350 keV) is 294 +- 71 sec (estimated error
including systematics).
The time-averaged spectrum from T-68.9 to T+405.1 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.54 +- 0.06. The fluence in the 15-150 keV band is 7.7 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+31.12 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/336489/BA/