TITLE: GCN CIRCULAR NUMBER: 18013 SUBJECT: GRB 150710B refined analysis DATE: 15/07/11 23:18:10 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), 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-47 to T+50 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150710B. (Cummings, et al., GCN Circ. 18009). The refined BAT position is RA, Dec = 83.191, -46.960 deg, which is RA(J2000) = 05h 32m 45.8s Dec(J2000) = -46d 57' 34" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows 6 overlapping but well-defined peaks followed by an exponential decay to background. T90 (15-350 keV) is 15 +- 1 sec (estimated error including systematics). The time-averaged spectrum from T+0 to T+15 sec is best fit by a model of a power law with an exponential cutoff. The photon index of the time-averaged spectrum is 0.99 +- 0.09. Epeak was 166 +- 28 keV. Using this model, the fluence in the 15-150 keV band was (3.5 +- 0.1) x 10^-6 ergs/cm^2. A simple power-law fit has a photon index of 1.34 +- 0.02. The 1-sec peak photon flux measured from T+3.5 sec in the 15-150 keV band was 8.3 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. A Swift TOO is being executed (Evans, GCN #18010). Because this was a ground-detected burst, the usual automated BAT data products are not available.