TITLE: GCN CIRCULAR NUMBER: 20565 SUBJECT: GRB 170127A: Swift-BAT refined analysis DATE: 17/01/29 16:00:54 GMT FROM: Amy Lien at GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), 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 170127A (trigger #735326) (Markwardt et al., GCN Circ. 20538). The BAT ground-calculated position is RA, Dec = 174.382, -45.827 deg which is RA(J2000) = 11h 37m 31.6s Dec(J2000) = -45d 49' 38.6" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%. The mask-weighted light curve shows some weak overlapping pulses that starts at ~T-5 s and ends at ~T+65 s. T90 (15-350 keV) is 62.26 +- 10.39 sec (estimated error including systematics). The time-averaged spectrum from T-4.65 to T+64.51 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.10 +- 0.30. The fluence in the 15-150 keV band is 5.2 +- 1.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+7.31 sec in the 15-150 keV band is 0.3 +- 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/735326/BA/