TITLE: GCN CIRCULAR NUMBER: 21458 SUBJECT: GRB 170810A: Swift-BAT refined analysis DATE: 17/08/11 15:26:06 GMT FROM: Takanori Sakamoto at AGU C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), S. L. Gibson (U Leicester), H. A. Krimm (NSF/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-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170810A (trigger #767284) (Gibson, et al., GCN Circ. 21450). The BAT ground-calculated position is RA, Dec = 187.928, 3.664 deg which is RA(J2000) = 12h 31m 42.8s Dec(J2000) = +03d 39' 49.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 93%. The mask-weighted light curve shows a complex multi-peaked structure that starts at ~T-20 s and ends at ~T+180 s. The brightest peak occurs at ~T+0.5 s. T90 (15-350 keV) is 152.4 +- 21.5 sec (estimated error including systematics). The time-averaged spectrum from T-24.33 to T+157.74 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.24 +- 0.07. The fluence in the 15-150 keV band is 4.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.15 sec in the 15-150 keV band is 1.2 +- 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/767284/BA/