TITLE:   GCN CIRCULAR
NUMBER:  28380
SUBJECT: GRB 200906A: Swift-BAT refined analysis
DATE:    20/09/07 16:58:46 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), K. L. Page (U Leicester),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (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 200906A (trigger #994856)
(Page et al., GCN Circ. 28371).  The BAT ground-calculated position is
RA, Dec = 272.284, 67.887 deg which is
   RA(J2000)  =  18h 09m 08.2s
   Dec(J2000) = +67d 53' 13.4"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 97%.

The mask-weighted light curve shows a double-peaked structure. The first
pulse starts at ~T-9 s and peaks at ~T+5 s. The second pulse starts
at ~T+46 s, peaks at ~T+51 s, and ends at ~T+90 s. T90 (15-350 keV)
is 70.90 +- 7.63 sec (estimated error including systematics).

The time-averaged spectrum from T-8.70 to T+90.01 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 2.00 +- 0.09.  The fluence in the 15-150 keV band
is 2.8 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
from T+50.96 sec in the 15-150 keV band is 2.5 +- 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/994856/BA/