TITLE: GCN CIRCULAR NUMBER: 6753 SUBJECT: GRB 070810B, Swift-BAT refined analysis DATE: 07/08/11 00:19:40 GMT FROM: Craig Markwardt at NASA/GSFC/UMD T. Sakamoto (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), F. E. Marshall (GSFC), D. Palmer (LANL), A. Parsons (GSFC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+303 sec from recent telemetry downlinks, we report further analysis of BAT GRB 070810B (trigger #287409) (Marshall, et al., GCN Circ. 6743). The BAT ground-calculated position is RA, Dec = 8.952, 8.822 deg which is RA(J2000) = 0h 35m 48.4s Dec(J2000) = 8d 49' 18" with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The light curve is a single FRED-like peak starting at T+0, and ending at T+0.12 sec. T90 (15-350 keV) is 80 +- 10 msec (estimated error including systematics). The time-averaged spectrum from T+0.008 to T+0.092 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.44 +- 0.37. The fluence in the 15-150 keV band is 1.2 +- 0.3 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.45 sec in the 15-150 keV band is 1.8 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence level.