TITLE: GCN CIRCULAR NUMBER: 41868 SUBJECT: GRB 250917B: Swift-BAT refined analysis DATE: 25/09/18 13:56:31 GMT FROM: Amy <yarleen@gmail.com> T. Parsotan (GSFC), S. D. Barthelmy (GSFC), R. Caputo (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), D. Sadaula (GSFC/UMBC), 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 250917B (trigger #1350381) (Caputo et al., GCN Circ. 41848). The BAT ground-calculated position is RA, Dec = 291.382, 11.117 deg which is RA(J2000) = 19h 25m 31.8s Dec(J2000) = +11d 06' 59.9" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 48%. The mask-weighted light curve shows a single FRED-like structure that starts at ~T-0.1, peaks at ~T0, and ends at ~T+0.4. T90 (15-350 keV) is 0.29 +- 0.08 sec (estimated error including systematics). The time-averaged spectrum from T+0.00 to T+0.37 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.66 +- 0.17. The fluence in the 15-150 keV band is 1.7 +- 0.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.31 sec in the 15-150 keV band is 2.4 +- 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/1350381 View this GCN Circular online at https://gcn.nasa.gov/circulars/41868. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...