TITLE: GCN CIRCULAR NUMBER: 14164 SUBJECT: GRB 130131B: Swift-BAT refined analysis DATE: 13/01/31 23:16:16 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Lien (GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), G. Sato (ISAS), M. H. Siegel (PSU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-119 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130131B (trigger #547420) (Siegel, et al., GCN Circ. 14159). The BAT ground-calculated position is RA, Dec = 173.957, 15.033 deg which is RA(J2000) = 11h 35m 49.6s Dec(J2000) = +15d 01' 59.3" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 51%. The mask-weighted light curve shows a single pulse starting at ~T-1 sec, peaking at ~T+0.5 sec, and ending at ~T+10 sec. T90 (15-350 keV) is 4.30 +- 0.26 sec (estimated error including systematics). The time-averaged spectrum from T-0.28 to T+4.37 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.15 +- 0.20. The fluence in the 15-150 keV band is 3.4 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.28 sec in the 15-150 keV band is 1.0 +- 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/547420/BA/