GCN Circular 11793
Subject
GRB 110315A: Swift-BAT refined analysis
Date
2011-03-16T13:47:11Z (13 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), N. Gehrels (GSFC), C. B. Markwardt (GSFC),
A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110315A (trigger #449399)
(Melandri, et al., GCN Circ. 11790). The BAT ground-calculated position is
RA, Dec = 279.205, 17.537 deg which is
RA(J2000) = 18h 36m 49.2s
Dec(J2000) = +17d 32' 13.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 57%.
The mask-weighted light curve shows a multi-peak structure starting
at ~T-70 sec, with several peaks of approximate equal brightness
at T-21, T-3, T+3, and T+17 sec, and then returning to background
at ~T+90 sec. There is weak emission (~2 sigma) in the BAT 15-25 keV band
starting at ~T+440 out to ~T+580 sec. This is likley associated with the flare
in the XRT lightcurve at ~T+500 sec. T90 (15-350 keV) is 77 +- 12 sec
(estimated error including systematics).
The time-averaged spectrum from T-66.8 to T+38.8 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.77 +- 0.08. The fluence in the 15-150 keV band is 4.1 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+3.13 sec in the 15-150 keV band
is 1.7 +- 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/449399/BA/