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GCN Circular 41234

Subject
GRB 250805A: Swift-XRT observations
Date
2025-08-05T07:51:10Z (18 days ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J.A. Kennea (PSU), G. Cusumano (INAF-IASF PA) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 250805A at 07:08:01.8 UT,
3532.9 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 24.20214,
-81.40161 which is equivalent to:
   RA(J2000)  = 01h 36m 48.51s
   Dec(J2000) = -81d 24' 05.8"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 30 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (8.44 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.6
(+3.34/-2.82) x 10^21 cm^-2 (90% confidence). 


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