TITLE: GCN CIRCULAR NUMBER: 35688 SUBJECT: GRB 240204A: Swift-BAT refined analysis DATE: 24/02/06 02:39:23 GMT FROM: Sibasish Laha at GSFC <sibasish.laha@nasa.gov> T. Sakamoto (AGU),S. D. Barthelmy (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), M. Stamatikos (OSU) (i.e. the Swift-BAT team): Swift-BAT triggered on GRB 240204A at 15:07:50.63 UT on 2024-02-04. Swift slewed immediately, but didn’t have initial BAT information due to a telemetry gap. Using the data set from T-239 to T+346 sec from the recent telemetry downlink, we report further analysis of BAT GRB 240204A (trigger #1212898) (Cenko, et al., GCN Circ. 35666). The BAT ground-calculated position is RA, Dec = 104.290, 1.078 deg which is RA(J2000) = 06h 57m 09.6s Dec(J2000) = +01d 04' 41.5" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 9%. The BAT light curve shows a complex structure with a duration of ~ 20 sec. T90 (15-350 keV) is 18.93 +- 2.06 sec (estimated error including systematics). The time-averaged spectrum from T-22.96 to T+8.96 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.21 +- 0.28, and Epeak of 67.8 +- 12.6 keV (chi squared 41.34 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.0 +- 0.0 x 10^-05 erg/cm2 and the 1-sec peak flux measured from T+0.08 sec in the 15-150 keV band is 22.1 +- 1.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.80 +- 0.06 (chi squared 55.74 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/1212898/BA/ View this GCN Circular online at https://gcn.nasa.gov/circulars/35688. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...