GCN Circular 40667

R. Gupta (GSFC), 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), D. Sadaula (GSFC/UMBC),
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 250605A (trigger #1321323)
(Gupta, et al., GCN Circ. 40633
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 ).  The BAT ground-calculated position is
RA, Dec = 166.963, -19.786 deg which is 
   RA(J2000)  =  11h 07m 51.1s 
   Dec(J2000) = -19d 47' 10.5" 
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.
 
The BAT light curve shows a complex light curve with multiple emission episodes:
a period of very dim extended emission between ~T0-100 sec to T0-10 leading up to  
one strong pulse between T0-10 sec to T0+10 sec and followed by a dim broad pulse 
between T0+40 sec to ~T0+125 sec. T90 (15-350 keV) is 176.05 +- 5.15 sec (estimated 
error including systematics).
 
The time-averaged spectrum from T-100.30 to T+126.69 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.50 +- 0.22, 
and Epeak of 76.7 +- 27.6 keV (chi squared 71.54 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.2 +- 0.0 x 10^-05 erg/cm2
and the 1-sec peak flux measured from T-0.00 sec in the 15-150 keV band is
6.1 +- 0.4 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.83 +- 0.05 (chi squared 79.05 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/1321323