TITLE:   GCN CIRCULAR
NUMBER:  31799
SUBJECT: GRB 220325A: Swift-BAT refined analysis
DATE:    22/03/28 15:14:06 GMT
FROM:    Sibasish Laha at GSFC  <sibasish.laha@nasa.gov>

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), A. Y. Lien (U Tampa)
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (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 220325A (trigger #1099310)
(Ferro et al., GCN Circ. 31787).  The BAT ground-calculated position is
RA, Dec = 269.469, -7.055 deg which is
   RA(J2000)  =  17h 57m 52.7s
   Dec(J2000) = -07d 03' 18.4"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 52%.

The BAT light curve showed a complex
structure with a duration of about 6 sec.
T90 (15-350 keV) is 3.50 +- 0.56 sec (estimated error including systematics).

The time-averaged spectrum from T-0.97 to T+3.02 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.69 +- 1.13,
and Epeak of 39.3 +- 8.9 keV (chi squared 63.15 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 2.9 +- 0.4 x 10^-07 erg/cm2
and the 1-sec peak flux measured from T+0.53 sec in the 15-150 keV band is
2.0 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.06 +- 0.17 (chi squared 69.80 for 57 d.o.f.).  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/1099310/BA/