GCN Circular 41252

T. Sakamoto (AGU), E. Ambrosi (INAF-IASFPA),
S. D. Barthelmy (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), D. Sadaula (GSFC/UMBC)
(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 250805A (trigger #1339848)
(Ambrosi, et al., GCN Circ. 41233
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 ).  The BAT ground-calculated position is
RA, Dec = 24.124, -81.400 deg which is 
   RA(J2000)  =  01h 36m 29.8s 
   Dec(J2000) = -81d 23' 59.0" 
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 65%.
 
The mask-weighted light curve displays a main emission period between T0-25 sec 
and T0+30 sec composed of multiple pulses with the strongest pulse beginning at T0. 
There is dim but significant emission beginning at T0-60 sec. The T90 (15-350 keV)
is 79.37 +- 11.98 sec (estimated error including systematics).
 
The time-averaged spectrum from T-60.66 to T+36.25 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.58 +- 0.53, 
and Epeak of 68.0 +- 15.8 keV (chi squared 54.47 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 2.2 +- 0.2 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+0.46 sec in the 15-150 keV band is
1.7 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.59 +- 0.11 (chi squared 67.84 for 57 d.o.f.).  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/1339848