GRB 081226A
GCN Circular 8735
Subject
GRB 081226A: Swift-BAT refined analysis
Date
2008-12-26T16:12:39Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
O. Godet (U Leicester) C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 081226A (trigger #338177)
(Godet, et al., GCN Circ. 8729). The BAT ground-calculated position is
RA, Dec = 120.478, -69.014 deg, which is
RA(J2000) = 08h 01m 54.6s
Dec(J2000) = -69d 00' 48.6"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.
The mask-weighted light curve shows a single spike starting at T+0.0 and
ending at T+0.4 sec. T90 (15-350 keV) is 0.4 +- 0.1 sec (estimated error
including systematics).
The time-averaged spectrum from T-0.1 to T+0.5 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.36 +- 0.29. The fluence in the 15-150 keV band is 9.9 +- 1.8 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.30 sec in the 15-150 keV band
is 2.4 +- 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/338177/BA/
GCN Circular 8737
Subject
GRB 081226A: Swift UVOT Upper Limits
Date
2008-12-26T18:03:45Z (16 years ago)
From
Erik Hoversten at Swift/Penn State <hoversten@astro.psu.edu>
E. A. Hoversten (PSU) and O. Godet (U Leicester) report on behalf of
the Swift UVOT team:
The Swift/UVOT began settled observations of the field of
GRB 08226A 156s after the BAT trigger (Godet et al., GCN 8729).
We do not detect any source at the Swift XRT position. The white
filter observation was skipped due to a 7th magnitude star in the field.
The UVOT upper limits are around 20th magnitude so the non-detections do
not conflict with the possible optical afterglow detections in GCN
8731 and GCN 8732 at 24th magnitude. UVOT magnitude 3-sigma upper
limits are reported in the following table:
Filter T_start T_stop Exp(s) Mag (3-sigma upper limit)
-------------------------------------------------------------
v 461 2276 233 > 19.24
b 410 2226 228 > 20.13
u 155 2051 833 > 20.87
uvw1 510 2176 213 > 19.71
uvm2 486 2151 213 > 19.51
uvw2 436 2252 233 > 19.83
The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight of E_(B-V) = 0.16 mag.
All photometry is on the UVOT photometric system described in Poole et
al. (2008, MNRAS, 383, 627).
GCN Circular 8785
Subject
Fermi/GBM detection of GRB 081226A
Date
2009-01-07T16:48:20Z (16 years ago)
From
Chryssa Kouveliotou at MSFC <chryssa.kouveliotou@nasa.gov>
Chryssa Kouveliotou (NASA/MSFC), Valerie Connaughton (UAHuntsville) report on behalf of the Fermi GBM Team:
"At 01:03:37.53 UT on 26 December 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081226 (trigger 251946218, trigcat 081226044), which was also detected by the SWIFT-BAT (Godet et al. 2008, GCN 8729). The on-ground calculated location, using the GBM trigger data, is RA = 119.01, DEC = -73.8 (J2000 degrees, equivalent to 07 h 56.04 m, -73 d 48'), with an uncertainty of 13.2 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 110 degrees.
The GBM light curve is a single pulse with a duration (T90) of about 1.7 s (20-775 keV). The time-averaged spectrum from T0-0.215 s to T0+0.233 s is best fit by a simple power law function with index 1.17 +/- 0.08 (chi squared 188 for 228 d.o.f.).
The event fluence (50-300 keV) in this time interval is (2.1 +/- 0.1)E-7 erg/cm^2. The 0.256-sec peak photon flux measured starting from T0-0.151 s in the 50-300 keV band is 3.2 +/- 0.1 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular 8952
Subject
Radio observation of GRB 081226a with ATCA
Date
2009-03-09T06:03:08Z (16 years ago)
From
Aquib Moin at CIRA/ATNF <aquib.moin@postgrad.curtin.edu.au>
Aquib Moin (Curtin Institute of Radio Astronomy / Australia Telescope
National Facility), Steven Tingay (Curtin Institute of Radio Astronomy),
Chris Phillips (Australia Telescope National Facility), Gregory Taylor
(University of New Mexico), Mark Wieringa (Australia Telescope National
Facility) and Ralph Martin (Perth Observatory) report:
We observed the GROND position of the GRB081226a afterglow (GCN 8731) at
4.800 and 4.928 GHz with the Australia Telescope Compact Array (ATCA)
between 01:00:00 UT and 22:00:00 UT on February 21/22, 2009.
We did not detect a radio source at the position of the GRB081226a (GCN
8731). The data at 4.800 and 4.928 GHz were merged and the radio flux
density at the GRB optical afterglow position found out to be 0.115 +/-
0.180 mJy/beam (1-sigma).
The Australia Telescope Compact Array (/ Parkes telescope / Mopra
telescope / Long Baseline Array) is part of the Australia Telescope
which is funded by the Commonwealth of Australia for operation as a
National Facility managed by CSIRO.
See the 4.800 & 4.928 GHz combined image at:
http://cira.ivec.org/dokuwiki/doku.php/grb/grb081226a/grb081226a_field_image