GCN Circular 40609
Subject
GRB 250530C: Swift-BAT refined analysis
Date
2025-06-02T19:11:33Z (4 days ago)
From
Mike Moss at NASA GSFC <mikejmoss3@gmail.com>
Via
Web form
D. Sadaula (GSFC/UMBC), S. D. Barthelmy (GSFC),
R. Caputo (NASA/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-240 to T+885 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 250530C (trigger #1319125)
(Caputo, et al., GCN Circ. 40585). The BAT ground-calculated position is
RA, Dec = 55.146, -22.457 deg which is
RA(J2000) = 03h 40m 35.1s
Dec(J2000) = -22d 27' 26.1"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.
The mask-weighted light curve displays a complex structure with multiple dim pulses.
The T90 (15-350 keV) is 42.86 +- 6.04 sec (estimated error including systematics).
The time-averaged spectrum from T-29.77 to T+21.26 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.32 +- 0.17. The fluence in the 15-150 keV band is 8.5 +- 0.9 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.28 sec in the 15-150 keV band
is 0.8 +- 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/1319125