TITLE:   GCN CIRCULAR
NUMBER:  23961
SUBJECT: GRB 190311A: Swift-BAT refined analysis
DATE:    19/03/12 16:23:39 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 190311A (trigger #892607)
(Troja et al., GCN Circ. 23946).  The BAT ground-calculated position is
RA, Dec = 212.067, 53.486 deg which is
  RA(J2000)  =  14h 08m 16.1s
  Dec(J2000) = +53d 29' 09.2"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 79%.

The mask-weighted light curve shows a single-pulse structure that starts
at ~T-2 s, peaks at ~T+1 s, and ends at ~T+20 s. T90 (15-350 keV) is
17.0 +- 6.8 sec (estimated error including systematics).

The time-averaged spectrum from T-2.22 to T+20.78 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.80 +- 0.17.  The fluence in the 15-150 keV band is 9.1 +- 0.9 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.78 sec in the 15-150 keV band
is 1.8 +- 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/892607/BA/