TITLE: GCN CIRCULAR NUMBER: 30513 SUBJECT: GRB 210724A: Swift-BAT refined analysis DATE: 21/07/25 19:43:26 GMT FROM: Amy Lien at GSFC S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF), 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+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210724A (trigger #1061482) (D'Avanzo et al., GCN Circ. 30497). The BAT ground-calculated position is RA, Dec = 227.425, -6.279 deg which is RA(J2000) = 15h 09m 41.9s Dec(J2000) = -06d 16' 42.9" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 34%. The mask-weighted light curve shows a multi-peaked structure that starts at ~T-40 s and ends at ~T+25 s. The main peak occurs at ~T0. T90 (15-350 keV) is 50.57 +- 9.54 sec (estimated error including systematics). The time-averaged spectrum from T-38.55 to T+25.50 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.30 +- 0.28. The fluence in the 15-150 keV band is 1.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.51 sec in the 15-150 keV band is 2.5 +- 0.8 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/1061482/BA/