TITLE:   GCN CIRCULAR
NUMBER:  39987
SUBJECT: GRB 250327A Swift-BAT refined analysis
DATE:    25/03/31 21:38:12 GMT
FROM:    Mike Moss at NASA GSFC <mikejmoss3@gmail.com>

S. D. Barthelmy (GSFC), R. Gupta (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. J. Moss (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC),
T. Sakamoto (AGU) (i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+843 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 250327A (trigger #1299088)
(Parsotan, et al., GCN Circ. 39877).  The BAT ground-calculated position is
RA, Dec = 248.209, 61.610 deg which is 
   RA(J2000)  =  16h 32m 50.1s 
   Dec(J2000) = +61d 36' 35.4" 
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 10%.
 
The mask-weighted light curve shows a single main pulse lasting ~60 sec composed
of several shorter pulses. The remainder of the burst emission is included in a 
dim tail. The T90 (15-350 keV) is 91.008 +- 12.21 sec (estimated error including 
systematics).
 
The time-averaged spectrum from T+1.67 to T+109.928 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.28 +- 0.12.  The fluence in the 15-150 keV band is 7.6 +- 0.5 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+24.49 sec in the 15-150 keV band
is 2.1 +- 0.7 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1299088