TITLE: GCN CIRCULAR NUMBER: 30863 SUBJECT: GRB 210919A: Swift-BAT refined analysis DATE: 21/09/22 22:04:47 GMT FROM: Sibasish Laha at GSFC <sibasish.laha@nasa.gov> S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tempa), C. B. Markwardt (GSFC), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210919A (trigger #1073893) (Tohuvavohu et al., GCN Circ. 30846). The BAT ground-calculated position is RA, Dec = 80.242, 1.286 deg which is RA(J2000) = 05h 20m 58.1s Dec(J2000) = +01d 17' 08.8" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The BAT light curve showed a short pulse of a duration ~ 1 sec. T90 (15-350 keV) is 0.16 +- 0.03 sec (estimated error including systematics). The time-averaged spectrum from T+0.05 to T+0.24 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.58 +- 0.27. The fluence in the 15-150 keV band is 8.8 +- 1.7 x 10^-08 erg/cm2. The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band is 1.5 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1073893/BA/