TITLE: GCN CIRCULAR NUMBER: 22099 SUBJECT: GRB 171103A: Swift-BAT refined analysis of a short GRB DATE: 17/11/04 21:58:58 GMT FROM: Amy Lien at GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (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 171103A (trigger #785850) (Ukwatta et al., GCN Circ. 22095). The BAT ground-calculated position is RA, Dec = 249.510, -10.206 deg which is RA(J2000) = 16h 38m 02.4s Dec(J2000) = -10d 12' 22.9" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 65%. The mask-weighted light curve shows a complex multi-peak structure. It begins with three peaks from -0.8 sec to +0.3 sec. This is followed by low-level, slowly decaying emission out to ~T+20 sec and then a weaker peak at ~T+60 sec. The spacecraft slewed away from the burst location at ~T+600 sec due to a pre-planned slew. T90 (15-350 keV) is 3.90 +- 1.11 sec (estimated error including systematics). The time-averaged spectrum from T-0.37 to T+4.67 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.31 +- 0.18. The fluence in the 15-150 keV band is 3.8 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.37 sec in the 15-150 keV band is 3.6 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The duration and hardness of this burst show it to be intermediate between the short and long burst populations. Using a 8-ms binned light curve, the lag analysis finds a lag of -0.5 +/- 4 ms for the 100-350 keV to 25-50 keV band, and -0.7 +/- 5 ms for the 50-100 keV to 15-25 keV band. These values are consistent with those of a short GRB. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/785850/BA/