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GCN Circular 31685

Subject
GRB 220305A: Swift-XRT observations
Date
2022-03-05T17:44:49Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
D.N. Burrows (PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB), G.
Cusumano (INAF-IASF PA), P.A. Evans (U. Leicester) and J.P. Osborne (U.
Leicester) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 220305A at 17:03:25.5 UT,
3016.9 seconds after the BAT trigger. Using promptly downlinked data we
find a fading, uncatalogued X-ray source located at RA, Dec 107.59841,
-37.68016 which is equivalent to:
   RA(J2000)  = 07h 10m 23.62s
   Dec(J2000) = -37d 40' 48.6"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 108 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 (2.59 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 8.1
(+6.60/-5.31) x 10^21 cm^-2 (90% confidence).
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