TITLE: GCN CIRCULAR NUMBER: 43355 SUBJECT: GRB 260104A: Swift-BAT refined analysis DATE: 26/01/09 03:01:10 GMT FROM: Tyler Parsotan at NASA GSFC <tyler.parsotan@nasa.gov> M. J. Moss (GSFC), S. D. Barthelmy (GSFC), R. Caputo (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 260104A (trigger #1430212) (Caputo, et al., GCN Circ. 43315). The BAT ground-calculated position is RA, Dec = 337.395, -21.291 deg which is RA(J2000) = 22h 29m 34.8s Dec(J2000) = -21d 17' 27.5" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 99%. The mask-weighted light curve shows two pulses. T90 (15-350 keV) is 13.26 +- 2.65 sec (estimated error including systematics). The time-averaged spectrum from T-10.09 to T+5.22 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.32 +- 1.08, and Epeak of 42.5 +- 8.8 keV (chi squared 67.04 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.5 +- 0.5 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T-0.23 sec in the 15-150 keV band is 1.3 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.85 +- 0.16 (chi squared 76.81 for 57 d.o.f.). 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/1430212 View this GCN Circular online at https://gcn.nasa.gov/circulars/43355. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...