GRB 241213A: Swift-BAT refined analysis

Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 241213A (trigger #1274039) (Gupta, et al., GCN Circ. 38547). The BAT ground-calculated position is RA, Dec = 116.163, 35.269 deg which is RA(J2000) = 07h 44m 39.2s Dec(J2000) = +35d 16' 06.7" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 44%. The mask-weighted light curve shows a single bright episode that starts at ~T-11 s, peaks at ~T+1 s and ends at ~T+16 s. T90 (15-350 keV) is 10.3 +- 3.1 sec (estimated error including systematics). The time-averaged spectrum from T-10.79 to T+16.54 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.26 +- 0.06. The fluence in the 15-150 keV band is 4.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.24 sec in the 15-150 keV band is 10.3 +- 0.5 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/1274039