TITLE: GCN CIRCULAR NUMBER: 37005 SUBJECT: GRB 240730A: Swift-BAT refined analysis DATE: 24/08/01 19:55:22 GMT FROM: Michael Moss at NASA GSFC mikejmoss3@gmail.com
D. Sadaula (GSFC/UMBC), S. D. Barthelmy (GSFC), S. B. Cenko (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), D. M. Palmer (LANL), T. Parsotan (GSFC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 240730A (trigger #1245636) (Cenko, et al., GCN Circ. 36976). The BAT ground-calculated position is RA, Dec = 37.841, 59.045 deg which is RA(J2000) = 02h 31m 21.9s Dec(J2000) = +59d 02' 43.5" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 98%.
The BAT mask-weighted light curve displays two spectrally soft peaks. The T90 (15-350 keV) is 50.13 +- 7.60 sec (estimated error including systematics).
The time-averaged spectrum from T-6.06 to T+53.43 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.50 +- 0.19. The fluence in the 15-150 keV band is 6.8 +- 0.9 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+5.80 sec in the 15-150 keV band is 0.4 +- 0.1 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/1245636
The long duration and proximity to the Galactic plane raised the initial possibility that this was a Galactic transient. However, its subsequent behavior, including a lack of later BAT detections, is consistent with a GRB, making the Galactic transient interpretation less likely.
View this GCN Circular online at https://gcn.nasa.gov/circulars/37005. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...