TITLE: GCN CIRCULAR NUMBER: 30839 SUBJECT: GRB 210912A: Swift-BAT refined analysis DATE: 21/09/13 23:34:08 GMT FROM: Sibasish Laha at GSFC <sibasish.laha@nasa.gov> M. Stamatikos (OSU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), (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 210912A (trigger #1072990) (Troja et al., GCN Circ. 30820). The BAT ground-calculated position is RA, Dec = 129.874, 79.216 deg which is RA(J2000) = 08h 39m 29.7s Dec(J2000) = +79d 12' 59.3" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The BAT light curve showed a complex structure with a duration of about ~30 sec. T90 (15-350 keV) is 28.35 +- 14.34 sec (estimated error including systematics). The time-averaged spectrum from T-23 to T+25 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.61 +- 0.13. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+0.23 sec in the 15-150 keV band is 1.7 +- 0.2 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/1072990/BA/