GCN Circular 37155
Subject
GRB 240811A: Swift-BAT refined analysis
Date
2024-08-12T18:07:11Z (2 months ago)
From
Tyler Parsotan at NASA GSFC <tyler.parsotan@nasa.gov>
Via
email
A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC),
R. Gupta (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), 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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 240811A (trigger #1248132)
(Page, et al., GCN Circ. 37136). The BAT ground-calculated position is
RA, Dec = 226.328, 28.884 deg which is
RA(J2000) = 15h 05m 18.8s
Dec(J2000) = +28d 53' 02.5"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.
The mask-weighted light curve shows a complex structure with many peaks and
potential precursor emission ~30 seconds before the trigger time.
T90 (15-350 keV) is 66.32 +- 5.22 sec (estimated error including systematics).
The time-averaged spectrum from T-42.95 to T+41.32 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.71 +- 0.08. The fluence in the 15-150 keV band is 3.0 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+11.30 sec in the 15-150 keV band
is 2.9 +- 0.3 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/1248132