TITLE: GCN CIRCULAR NUMBER: 14163 SUBJECT: GRB 130131A: Swift-BAT refined analysis DATE: 13/01/31 23:03:50 GMT FROM: Scott Barthelmy at NASA/GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), D. Grupe (PSU), H. A. Krimm (GSFC/USRA), A. Lien (GSFC/ORAU), C. B. Markwardt (GSFC), 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-239 to T+903 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130131A (trigger #547407) (Grupe, et al., GCN Circ. 14156). The BAT ground-calculated position is RA, Dec = 171.091, 48.064 deg which is RA(J2000) = 11h 24m 21.9s Dec(J2000) = +48d 03' 51.0" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%. The mask-weighted light curve shows two separated peaks: (1) starting at ~T-5 sec, peaking at ~T+1 sec, and ending at ~T+15 sec, and (2) T+35, T+47, and ~T+65 sec. T90 (15-350 keV) is 51.6 +- 2.4 sec (estimated error including systematics). The time-averaged spectrum from T-0.95 to T+52.15 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.12 +- 0.32. The fluence in the 15-150 keV band is 3.1 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.04 sec in the 15-150 keV band is 0.7 +- 0.1 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/547407/BA/