TITLE: GCN CIRCULAR NUMBER: 37356 SUBJECT: GRB 240829A: Swift-BAT refined analysis DATE: 24/08/31 00:25:46 GMT FROM: Michael Moss at NASA GSFC mikejmoss3@gmail.com

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

Using the data set from T-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 240829A (trigger #1251252) (Laha, et al., GCN Circ. 37333). The BAT ground-calculated position is RA, Dec = 143.079, -18.687 deg which is RA(J2000) = 09h 32m 18.9s Dec(J2000) = -18d 41' 13.0" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 15%.

The mask-weighted light curve displays a combination of two to three dim fast- rise-exponential-decay pulses. The T90 (15-350 keV) is 43.20 +- 10.47 sec (estimated error including systematics).

The time-averaged spectrum from T-12.53 to T+51.47 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.66 +- 0.11. The fluence in the 15-150 keV band is 3.8 +- 0.3 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+10.97 sec in the 15-150 keV band is 0.0 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.

Swift did not slew to the BAT position due to the burst being sun constrained.

The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1251252

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