TITLE: GCN CIRCULAR NUMBER: 18944 SUBJECT: GRB 160127A: Swift-BAT refined analysis DATE: 16/01/27 18:48:10 GMT FROM: Amy Lien at GSFC S. D. Barthelmy (GSFC), A. Amaral-Rogers (U Leicester), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 160127A (trigger #671828) (Amaral-Rogers et al., GCN Circ. 18938). The BAT ground-calculated position is RA, Dec = 225.966, 0.080 deg which is RA(J2000) = 15h 03m 51.8s Dec(J2000) = +00d 04' 46.7" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 41%. The mask-weighted light curve shows a double-peaked structure that starts at ~ T-1 s and ends at ~ T+6 s. The two peaks occur at ~ T+1 and ~T+3 s, respectively. T90 (15-350 keV) is 6.16 +- 0.94 sec (estimated error including systematics). The time-averaged spectrum from T-1.44 to T+5.70 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.99 +- 1.11, and Epeak of 25.6 +- 0.0 keV (chi squared 44.15 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.3 +- 0.5 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+3.34 sec in the 15-150 keV band is 1.4 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.43 +- 0.23 (chi squared 50.23 for 57 d.o.f.). 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/671828/BA/