TITLE: GCN CIRCULAR NUMBER: 13942 SUBJECT: GRB 121102A: Swift-BAT refined analysis DATE: 12/11/02 12:13:27 GMT FROM: Scott Barthelmy at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 121102A (trigger #537266) (D'Elia, et al., GCN Circ. 13938). The BAT ground-calculated position is RA, Dec = 270.896, -16.951 deg, which is RA(J2000) = 18h 03m 35.1s Dec(J2000) = -16d 57' 03.4" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a FED peak starting at ~T-0.2 sec, peaking at ~T+6 sec, and ending at ~T+95 sec. T90 (15-350 keV) is 24.7 +- 3.4 sec (estimated error including systematics). The time-averaged spectrum from T-0.30 to T+35.25 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.88 +- 0.07. The fluence in the 15-150 keV band is 1.9 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+5.68 sec in the 15-150 keV band is 2.3 +- 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/537266/BA/