[vsnet-grb-info 8299] GRB 090815C: Swift refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9824
SUBJECT: GRB 090815C: Swift refined analysis
DATE:    09/08/17 20:41:44 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), P.A. Evans (U. Leicester)
on behalf of the Swift Team:

At 23:21:39 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090815C (trigger=360068).  No GCN Notices were issued
because the trigger was below the normal acceptance level.  Also,
the spacecraft did not execute an automated slew to the location
because of an Earth observing constraint.  Later, ground-processing
using the full data set T-60 to T+303 sec determined the location to be
RA, Dec = 64.490, -65.943 deg, which is
   RA(J2000)  =  04h 17m 57.6s
   Dec(J2000) = -65d 56' 33.5"
with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 76%.

The BAT mask-weighted light curve shows a single weak peak.  T90 (15-350 keV)
is 0.6 +- 0.3 sec (estimated error including systematics).

The time-averaged spectrum from T-0.0 to T+0.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.90 +- 0.47.  The fluence in the 15-150 keV band is 4.4 +- 1.2 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.18 sec in the 15-150 keV band
is 0.6 +- 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/360068/BA/

Based on the ground-processing of the full BAT data, a ToO was executed
6.1 hours after the trigger.  Swift-XRT obtained 4.3 ks of Photon Counting
(PC) mode data, from T0+22 ks to T0+56 ks.  No source is found in the BAT
error circle, with a 3-sigma upper limit of 1.9 x 10^-3 ct/sec;
for a typical GRB, this corresponds to an upper limit on the observed
0.3-10 keV flux of 7 x 10^-14 erg cm^-2 s^-1.