[vsnet-grb-info 8323] GRB 090827 Burst discovered in BAT ground analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9846
SUBJECT: GRB 090827 Burst discovered in BAT ground analysis
DATE:    09/08/28 20:39:11 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <jayc at milkyway.gsfc.nasa.gov>

J. R. Cummings (GSFC/UMBC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC/UMD), and D. M. Palmer (LANL),
on behalf of the Swift-BAT team

At 19:06:26 on 2009-08-27, GRB 090827 triggered Swift-BAT
(trigger #361029). No source was found onboard.  A source
was found in ground analysis of BAT event data.  The burst
consisted of a single pulse of 7 seconds.  This burst also
triggered Konus-Wind and INTEGRAL-SPI-ACS (V. Pal'shin,
private communication).

The BAT position is RA, Dec 18.435, -50.899, which is
equivalent to:

       RA, Dec (J2000): 01:13:44.4, -50d 53' 58"  	

with an uncertainty radius of 2.8 arcmin (estimated 90%
containment, stat+sys). The source was 3% coded.

Because of the extreme partial coding, the spectral parameters
can be defined only poorly.  The spectrum is best fit by a
simple powerlaw relation.  The photon index is 1.0 +/- 0.3.
The fluence was (4 +/- 2) x 10^-6 ergs/cm2. The errors are
estimated 1-sigma.

A Swift TOO has been requested and will take place
starting approximately 26 hours after the burst.