TITLE: GCN CIRCULAR NUMBER: 35523 SUBJECT: GRB 240109A: Swift-BAT refined analysis DATE: 24/01/12 18:37:07 GMT FROM: Sibasish Laha at GSFC <sibasish.laha@nasa.gov> D. M. Palmer (LANL), 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), T. Parsotan (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 240109A (trigger #1207446) (Dichiara et al., GCN Circ. 35501). The BAT ground-calculated position is RA, Dec = 301.330, 16.566 deg which is RA(J2000) = 20h 05m 19.1s Dec(J2000) = +16d 33' 58.3" with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%. The BAT light curve shows a single peak with a duration ~0.5 sec. T90 (15-350 keV) is 0.16 +- 0.06 sec (estimated error including systematics). The time-averaged spectrum from T-0.04 to T+0.15 sec is better fit by a blackbody. A simple power-law fit shows a photon index of 2.75 +-0.35 with a poor statistics (reduced chi2 of 1.9). Instead, the black body fit shows the temperature of 12.2 +-1.3 keV with a reasonable statistics (reduced chi2 of 1.2). So, the burst prefers a soft spectrum. The fluence in the 15-150 keV band is 1.2 +- 0.4 x 10^-08 erg/cm2. The 1-sec peak photon flux measured from T-0.44 sec in the 15-150 keV band is 0.7 +- 0.2 ph/cm2/sec. 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/1207446/BA/ View this GCN Circular online at https://gcn.nasa.gov/circulars/35523. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...