TITLE: GCN CIRCULAR NUMBER: 42366 SUBJECT: GRB 251017A: Swift-BAT refined analysis DATE: 25/10/19 01:53:31 GMT FROM: Rahul Gupta at NASA GSFC rahul.gupta@nasa.gov

T. Parsotan (GSFC), 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), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):

Using the data set from T-60 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251017A (trigger #1404904) (Gupta, et al., GCN Circ. 42322). The BAT ground-calculated position is RA, Dec = 335.404, 7.048 deg which is RA(J2000) = 22h 21m 37.0s Dec(J2000) = +07d 02' 54.4" with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 93%.

The mask-weighted BAT light curve shows main emission followed by weaker emission. T90 (15-350 keV) is 116.90 +- 61.91 sec (estimated error including systematics).

The time-averaged spectrum from T-5.48 to T+125.08 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.40 +- 0.20. The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+6.41 sec in the 15-150 keV band is 1.3 +- 0.2 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/1404904

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