TITLE: GCN CIRCULAR NUMBER: 20129 SUBJECT: GRB 161104A, Swift-BAT refined analysis DATE: 16/11/05 02:14:12 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), B. Mingo (U Leicester), J. P. Norris (BSU), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+150 sec from the recent telemetry downlink, we report further analysis of BAT GRB 161104A (trigger #720568) (Mingo, et al., GCN Circ. 20123). The BAT ground-calculated position is RA, Dec = 77.906, -51.447 deg which is RA(J2000) = 05h 11m 37.3s Dec(J2000) = -51d 26' 49.7" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 99%. The mask-weighted light curve shows a single spike that starts at at ~T-0.02, peaks at ~T+0.02, and ends at~T+0.1. T90 (15-350 keV) is 0.1 +- 0.02 sec (estimated error including systematics). The time-averaged spectrum from T-0.0 to T+0.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.57 +- 0.20. The fluence in the 15-150 keV band is 3.1 +- 0.5 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.46 sec in the 15-150 keV band is 0.6 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Using a 4-ms binned light curve, the lag analysis finds a lag of 2.0 +/- 8.0 ms for the 100-350 keV to 25-50 keV band, and -3.5 +/- 8.0 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/720568/BA/ [GCN OPS NOTE05nov16): Per author's request, JN as was added to the author list.]