TITLE: GCN CIRCULAR NUMBER: 27443 SUBJECT: GRB 200324A, Swift-BAT refined analysis DATE: 20/03/25 21:13:14 GMT FROM: Amy Lien at GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), S. Dichiara (NASA/GSFC/UMCP), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU) (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 200324A (trigger #963260) (Dichiara et al., GCN Circ. 27428). The BAT ground-calculated position is RA, Dec = 222.682, 35.931 deg which is RA(J2000) = 14h 50m 43.7s Dec(J2000) = +35d 55' 51.0" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a weak pulse that starts at ~T-40 s, peaks at ~T0, and lasts until >~T+80 s. The burst was temporarily out of the BAT FOV from T+100.39 s to T+119.39 s. There might be additional burst emission during this period. Due to this data gap, the standard data analysis pipeline is unable to estimate an accurate T90. The time-averaged spectrum from T-38.1 to T+100.4 sec (before the burst went out of the BAT FOV) is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.72 +- 0.15. The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.07 sec in the 15-150 keV band is 0.7 +- 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/963260/BA/