TITLE: GCN CIRCULAR NUMBER: 29754 SUBJECT: GRB 210403A: Swift-BAT refined analysis DATE: 21/04/03 20:57:12 GMT FROM: Scott Barthelmy at NASA/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-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210403A (trigger #1040345) (K.Page, et al., GCN Circ. 29748). The BAT ground-calculated position is RA, Dec = 2.813, -33.024 deg which is RA(J2000) = 00h 11m 15.2s Dec(J2000) = -33d 01' 27.2" with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 80%. The lightcurve has multiple peaks starting at T-40 sec and ending at T+140 sec. T90 (15-350 keV) is 168.3 +- 9.2 sec (estimated error including systematics). The time-averaged spectrum from T-41.51 to T+137.18 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.93 +- 0.52, and Epeak of 37.4 +- 4.8 keV (chi squared 52.21 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.7 +- 0.2 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+0.18 sec in the 15-150 keV band is 1.1 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.13 +- 0.10 (chi squared 73.02 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/1040345/BA/