GCN Circular 10121
Subject
GRB 091102: Swift-BAT refined analysis
Date
2009-11-02T22:06:25Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), E. A. Hoversten (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 091102 (trigger #374598)
(Hoversten, et al., GCN Circ. 10117). The BAT ground-calculated position is
RA, Dec = 72.622, -72.527 deg which is
RA(J2000) = 04h 50m 29.3s
Dec(J2000) = -72d 31' 37.9"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.
Because the s/c slewed for an observing constraint, the burst location
went out of the BAT FOV at T+160 sec, and then came back into the FOV
at T+900 sec. The mask-weighted light curve shows a couple slightly overlapping
peaks starting at ~T-2 sec, and ending at ~T+20 sec. There is now measurable
flux at T+900 sec when the location comes back into the FOV. T90 (15-350 keV)
is 6.6 +- 0.5 sec (estimated error including systematics).
The time-averaged spectrum from T-0.8 to T+6.6 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.08 +- 0.12. The fluence in the 15-150 keV band is 5.2 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.26 sec in the 15-150 keV band
is 1.4 +- 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/374598/BA/