TITLE: GCN CIRCULAR NUMBER: 41321 SUBJECT: GRB 250809A: Swift-BAT refined analysis DATE: 25/08/11 18:09:12 GMT FROM: D. R. Sadaula at NASA GSFC <dev.r.sadaula@nasa.gov> D. Sadaula (GSFC/UMBC), 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), T. Sakamoto (AGU) (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 250809A (trigger #1340954) (Parsotan, et al., GCN Circ. 41303). The BAT ground-calculated position is RA, Dec = 233.034, -53.314 deg which is RA(J2000) = 15h 32m 08.2s Dec(J2000) = -53d 18' 50.6" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The BAT light curve showed a complex structure with a duration of about 32 sec. T90 (15-350 keV) is 17.79 +- 2.77 sec (estimated error including systematics). The time-averaged spectrum from T+1.01 to T+20.94 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.83 +- 0.20. The fluence in the 15-150 keV band is 3.9 +- 0.5 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+11.58 sec in the 15-150 keV band is 0.6 +- 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/1340954 View this GCN Circular online at https://gcn.nasa.gov/circulars/41321. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...