TITLE: GCN CIRCULAR NUMBER: 40565 SUBJECT: GRB 250520A: Swift-BAT refined analysis DATE: 25/05/28 20:11:35 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov> R. Gupta (GSFC), S. D. Barthelmy (GSFC), R. A. J. Eyles-Ferris (U Leicester), 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), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+200 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250520A (trigger #1315630) (Eyles-Ferris, et al., GCN Circ. 40491). The BAT ground-calculated position is RA, Dec = 282.265, -11.852 deg which is RA(J2000) = 18h 49m 03.6s Dec(J2000) = -11d 51' 08.6" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 68%. The mask-weighted BAT light curve exhibits a single pulsed emission. T90 (15-350 keV) is 0.46 +- 0.15 sec (estimated error including systematics). The time-averaged spectrum from T-0.33 to T+0.23 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.55 +- 0.23. The fluence in the 15-150 keV band is 1.8 +- 0.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.54 sec in the 15-150 keV band is 1.9 +- 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/1315630 View this GCN Circular online at https://gcn.nasa.gov/circulars/40565. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...