TITLE: GCN CIRCULAR NUMBER: 39987 SUBJECT: GRB 250327A Swift-BAT refined analysis DATE: 25/03/31 21:38:12 GMT FROM: Mike Moss at NASA GSFC mikejmoss3@gmail.com
S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+843 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250327A (trigger #1299088) (Parsotan, et al., GCN Circ. 39877). The BAT ground-calculated position is RA, Dec = 248.209, 61.610 deg which is RA(J2000) = 16h 32m 50.1s Dec(J2000) = +61d 36' 35.4" with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 10%.
The mask-weighted light curve shows a single main pulse lasting ~60 sec composed of several shorter pulses. The remainder of the burst emission is included in a dim tail. The T90 (15-350 keV) is 91.008 +- 12.21 sec (estimated error including systematics).
The time-averaged spectrum from T+1.67 to T+109.928 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.28 +- 0.12. The fluence in the 15-150 keV band is 7.6 +- 0.5 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+24.49 sec in the 15-150 keV band is 2.1 +- 0.7 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1299088
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