TITLE: GCN CIRCULAR NUMBER: 41539 SUBJECT: GRB 250823A: Swift-BAT refined analysis DATE: 25/08/25 12:44:24 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov> C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU), M. H. Siegel (PSU) (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 250823A (trigger #1344586) (Siegel, et al., GCN Circ. 41511). The BAT ground-calculated position is RA, Dec = 297.465, -24.986 deg which is RA(J2000) = 19h 49m 51.7s Dec(J2000) = -24d 59' 09.0" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%. The mask-weighted BAT light curve shows multi-peaked emission starting from ~T-25 to ~T+180 sec. T90 (15-350 keV) is 193.60 +- 10.19 sec (estimated error including systematics). The time-averaged spectrum from T-23.84 to T+180.82 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.76 +- 0.16. 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+4.24 sec in the 15-150 keV band is 1.1 +- 0.2 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/1344586 View this GCN Circular online at https://gcn.nasa.gov/circulars/41539. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...