TITLE:   GCN CIRCULAR
NUMBER:  33541
SUBJECT: GRB 230328B: Swift-BAT refined analysis
DATE:    23/03/30 03:44:23 GMT
FROM:    Tyler Parsotan at UMBC/GSFC/CRESST II  <parsotat@umbc.edu>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), 

H. A. Krimm (NSF), S. Laha (GSFC/UMBC),

A. Y. Lien (U Tampa), 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+963 sec from the recent telemetry downlink,

we report further analysis of BAT GRB 230328B (trigger #1162001)

(Gropp, et al., GCN Circ. 33527).  The BAT ground-calculated position is

RA, Dec = 291.037, 80.013 deg which is 

   RA(J2000)  =  19h 24m 08.8s 

   Dec(J2000) = +80d 00' 45.3" 

with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).

The partial coding was 46%.

 

The mask weighted light curve has a double peaked structure.

The light curve does not show an early afterglow as was stated in the original GCN. 

T90 (15-350 keV) is 19.23 +- 3.82 sec (estimated error including systematics).

 

The time-averaged spectrum from T-7.38 to T+25.49 sec is best fit by a power law

with an exponential cutoff.  This fit gives a photon index 1.22 +- 0.29, 

and Epeak of 99.7 +- 59.7 keV (chi squared 29.53 for 56 d.o.f.).  For this

model the total fluence in the 15-150 keV band is 4.3 +- 0.2 x 10^-06 erg/cm2

and the 1-sec peak flux measured from T+0.26 sec in the 15-150 keV band is

8.4 +- 0.5 ph/cm2/sec.  A fit to a simple power law gives a photon index

of 1.63 +- 0.07 (chi squared 35.85 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/1162001/BA/