GCN Circular 10103
Subject
GRB 091029: Swift-BAT refined analysis
Date
2009-10-29T13:30:45Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), D. Grupe (PSU),
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), T. N. Ukwatta (GWU)
(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 091029 (trigger #374210)
(Grupe, et al., GCN Circ. 10097). The BAT ground-calculated position is
RA, Dec = 60.166, -55.954 deg, which is
RA(J2000) = 04h 00m 40.0s
Dec(J2000) = -55d 57' 12.7"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 99%.
The mask-weighted light curve shows three overlapping peaks, the first starting
at ~T-10 sec, peaking at T+2, +20, and +26 sec, and ending at ~T+70 sec.
T90 (15-350 keV) is 39.2 +- 5 sec (estimated error including systematics).
The time-averaged spectrum from T-1.8 to T+60.2 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.46 +- 0.27,
and Epeak of 61.4 +- 17.5 keV (chi squared 49.9 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 2.4 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+19.12 sec in the 15-150 keV band is
1.8 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.88 +- 0.06 (chi squared 57.4 for 57 d.o.f.). 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/374210/BA/