TITLE: GCN CIRCULAR NUMBER: 30207 SUBJECT: GRB 210610B: Swift-BAT refined analysis DATE: 21/06/11 19:08:46 GMT FROM: Amy Lien at GSFC H. A. Krimm (NSF), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), K. L. Page (U Leicester), 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+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210610B (trigger #1054681) (Page et al., GCN Circ. 30170). The BAT ground-calculated position is RA, Dec = 243.929, 14.398 deg which is RA(J2000) = 16h 15m 42.8s Dec(J2000) = +14d 23' 54.5" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 24%. The mask-weighted light curve shows several overlapping pulses that start at ~T-12 and end at ~T+140 s. The main peak occurs at ~T+8 s. T90 (15-350 keV) is 69.38 +- 2.53 sec (estimated error including systematics). The time-averaged spectrum from T-12.04 to T+142.47 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.98 +- 0.11, and Epeak of 339.3 +- 218.6 keV (chi squared 27.43 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.6 +- 0.1 x 10^-5 erg/cm2 and the 1-sec peak flux measured from T+7.95 sec in the 15-150 keV band is 13.5 +- 0.7 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.17 +- 0.03 (chi squared 36.54 for 57 d.o.f.). 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/1054681/BA/