GRB 200922A: Swift-BAT refined analysis
Abstract
Using the data set from T-239 to T+871 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200922A (trigger #997024) (Moss et al., GCN Circ. 28471). The BAT ground-calculated position is RA, Dec = 296.954, -55.199 deg which is RA(J2000) = 19h 47m 49.0s Dec(J2000) = -55d 11' 55.1" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 74%. The mask-weighted light curve shows a single FRED-like pulse that starts at ~T-2 s, peaks at ~T+0, and ends at ~T+16 s. T90 (15-350 keV) is 10.30 +- 1.96 sec (estimated error including systematics). The time-averaged spectrum from T-1.91 to T+16.22 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.43 +- 0.26, and Epeak of 39.3 +- 5.7 keV (chi squared 52.48 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.8 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T-0.46 sec in the 15-150 keV band is 11.4 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.12 +- 0.06 (chi squared 76.50 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/997024/BA/
- Publication:
-
GRB Coordinates Network
- Pub Date:
- September 2020
- Bibcode:
- 2020GCN.28484....1S