TITLE: GCN CIRCULAR NUMBER: 15293 SUBJECT: GRB 131001A, Swift-BAT refined analysis DATE: 13/10/02 23:18:50 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): We report further analysis of BAT GRB 131001A (Cummings, GCN Circ. 15281). The BAT ground-calculated position is RA, Dec = 8.304, 25.557 deg which is RA(J2000) = 00h 33m 13.0s Dec(J2000) = +25d 33' 26" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The mask-weighted light curve shows a single FRED peak. T90 (15-350 keV) is 4.9 +- 0.3 sec (estimated error including systematics). The time-averaged spectrum from T0 to T+5 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.8 +- 0.6, and Epeak of 55 +- 14 keV (chi squared 55.6 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.9 +- 0.6 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+5.49 sec in the 15-150 keV band is 2.57 +- 0.25 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.81 +- 0.12 (chi squared 66.2 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. Since this burst was ground-detected the usual automated results of the batgrbproduct analysis are not available.