GCN Circular 33880

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), R. A. J. Eyles-Ferris (U Leicester), H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+349 sec from the recent telemetry downlink, we report further analysis of BAT GRB 230510A (trigger #1167973) (Eyles-Ferris, et al., GCN Circ. 33752). The BAT ground-calculated position is RA, Dec = 318.138, 34.430 deg which is RA(J2000) = 21h 12m 33.2s Dec(J2000) = +34d 25' 49.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a precursor starting at T-150 s with a duration of ~20 s. The bright main episode starts at T-10 s, peaks at T+15 s, and ends at T+60 s. T90 (15-350 keV) is 178.4 +- 6.9 sec (estimated error including systematics). The time-averaged spectrum from T-145.6 to T+56.8 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.60 +- 0.09. The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+13.39 sec in the 15-150 keV band is 5.9 +- 0.3 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/1167973/BA/