TITLE:   GCN CIRCULAR
NUMBER:  36928
SUBJECT: GRB 240720A: Swift-BAT refined analysis
DATE:    24/07/23 20:52:12 GMT
FROM:    Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov>

T. Sakamoto (AGU), 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)(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 240720A (trigger #1243868)
(Gupta, et al., GCN Circ. 36909).  The BAT ground-calculated position is
RA, Dec = 96.728, 30.297 deg which is
   RA(J2000)  =  06h 26m 54.6s
   Dec(J2000) = +30d 17' 48.3"
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 57%.

The mask-weighted BAT light curve shows a short hard spike, followed by an extended softer emission with a duration of ~ 200 sec. T90 (15-350 keV) is 181.85 +- 73.84 sec (estimated error including systematics).

The time-averaged spectrum from T-0.12 to T+193.92 sec is best fit by a simple power-law model.  The power law index of the time-averaged spectrum is 1.47 +- 0.22.  The fluence in the 15-150 keV band is 1.8 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+0.44 sec in the 15-150 keV band is 2.5 +- 0.3 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/1243868