TITLE:   GCN CIRCULAR
NUMBER:  34085
SUBJECT: GRB 230618A: Swift-BAT refined analysis
DATE:    23/06/27 00:39:58 GMT
FROM:    Sibasish Laha at GSFC <sibasish.laha@nasa.gov>

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-275 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230618A (trigger #1175438)
(Page et al., GCN Circ. 33989).  The BAT ground-calculated position is
RA, Dec = 196.642, 3.278 deg which is
   RA(J2000)  =  13h 06m 34.1s
   Dec(J2000) = +03d 16' 39.6"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The BAT light curve showed a complex structure with a duration of about 200 sec.
T90 (15-350 keV) is 104.05 +- 22.86 sec (estimated error including systematics).

The time-averaged spectrum from T-27.78 to T+107.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.35 +- 0.15.  The fluence in the 15-150 keV band is 1.5 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+9.04 sec in the 15-150 keV band
is 0.5 +- 0.1 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/1175438/BA/