GCN Circular 9736
Subject
GRB 090728: Swift-BAT refined analysis
Date
2009-07-29T20:08:49Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
D. M. Palmer (LANL), 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), V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD),
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 recent telemetry downlinks,
we report further analysis of BAT GRB 090728 (trigger #358574)
(Mangano, et al., GCN Circ. 9725). The BAT ground-calculated position is
RA, Dec = 29.644, 41.632 deg which is
RA(J2000) = 01h 58m 34.5s
Dec(J2000) = +41d 37' 53.7"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 37%.
The mask-weighted light curve shows a single pulse starting at ~T-10 sec,
peaking at ~T+2 sec, and ending at ~T+70 sec. T90 (15-350 keV) is
59 +- 18 sec (estimated error including systematics).
The time-averaged spectrum from T-5.0 to T+63.2 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.05 +- 0.26. The fluence in the 15-150 keV band is 1.0 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.25 sec in the 15-150 keV band
is 1.0 +- 0.3 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/358574/BA/