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GCN Circular 35702

Subject
GRB 240205B: Swift-BAT refined analysis
Date
2024-02-07T19:18:03Z (16 days ago)
From
Sibasish Laha at GSFC <sibasish.laha@nasa.gov>
Via
email
M. Stamatikos (OSU), S. D. Barthelmy (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+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 240205B (trigger #1213095)
(Moss, et al., GCN Circ. 35683).  The BAT ground-calculated position is
RA, Dec = 351.466, -55.123 deg which is
   RA(J2000)  =  23h 25m 51.9s
   Dec(J2000) = -55d 07' 24.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.

The BAT light curve shows a complex structure with a duration of ~ 60 sec.
Above 100 keV, the lightcurve is dominated by a single bright 1 s long peak around T+40.
A similar feature has also been reported by GECAM-B telescope, Zhang et al., GCN circ. 35689.
T90 (15-350 keV) is 47.29 +- 0.29 sec (estimated error including systematics).

The time-averaged spectrum from T-0.84 to T+78.94 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.23 +- 0.03.  The fluence in the 15-150 keV band is 2.6 +- 0.0 x 10^-05 erg/cm2.
The 1-sec peak photon flux measured from T+39.07 sec in the 15-150 keV band
is 47.8 +- 1.0 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1213095/BA/

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