TITLE:   GCN CIRCULAR
NUMBER:  33880
SUBJECT: GRB 230510A: Swift-BAT refined analysis
DATE:    23/05/26 13:27:36 GMT
FROM:    Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), R. A. J. Eyles-Ferris (U Leicester),
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+349 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230510A (trigger #1167973)
(Eyles-Ferris, et al., GCN Circ. 33752).  The BAT ground-calculated position is
RA, Dec = 318.138, 34.430 deg which is
   RA(J2000)  =  21h 12m 33.2s
   Dec(J2000) = +34d 25' 49.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 The mask-weighted light curve shows a precursor starting at T-150 s with
a duration of ~20 s.  The bright main episode starts at T-10 s, peaks at
T+15 s, and ends at T+60 s.  T90 (15-350 keV) is 178.4 +- 6.9 sec
(estimated error including systematics).
 The time-averaged spectrum from T-145.6 to T+56.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.60 +- 0.09.  The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+13.39 sec in the 15-150 keV band
is 5.9 +- 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/1167973/BA/