TITLE:   GCN CIRCULAR
NUMBER:  30839
SUBJECT: GRB 210912A: Swift-BAT refined analysis
DATE:    21/09/13 23:34:08 GMT
FROM:    Sibasish Laha at GSFC  <sibasish.laha@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
(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 210912A (trigger #1072990)
(Troja et al., GCN Circ. 30820).  The BAT ground-calculated position is
RA, Dec = 129.874, 79.216 deg which is
   RA(J2000)  =  08h 39m 29.7s
   Dec(J2000) = +79d 12' 59.3"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The BAT light curve showed a complex structure with a duration of about ~30 sec.
T90 (15-350 keV) is 28.35 +- 14.34 sec (estimated error including systematics).

The time-averaged spectrum from T-23 to T+25 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.61 +- 0.13.  The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+0.23 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/1072990/BA/