[vsnet-grb-info 28444] GRB 210724A: Corrected Swift-XRT enhanced position
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Fri Jul 30 00:26:43 JST 2021
TITLE: GCN CIRCULAR
NUMBER: 30547
SUBJECT: GRB 210724A: Corrected Swift-XRT enhanced position
DATE: 21/07/29 15:25:48 GMT
FROM: Phil Evans at U of Leicester <pae9 at leicester.ac.uk>
P.A. Evans (U. Leicester) and P. D'Avanzo (INAF-OAB) report on behalf of
the Swift-XRT team.
The XRT position of GRB 210724A reported in GCN Circ. 30515 was 11" from
the position of the optical candidate found by de Ugarte Postigo et al.
(GCN Circ. 30511). Unusually, this position underwent significant
variation during the normal revisions after each data downlink.
Investigation has revealed a rare local minimum issue during the first
XRT image, which has now been fixed.
The best XRT position is RA, Dec = 227.41461, -6.29070 which is
equivalent to:
RA (J2000): 15h 09m 39.51s
Dec(J2000): -06d 17' 26.5"
with an uncertainty of 3.0 arcsec (radius, 90% confidence). This
position is 1.1" from the optical position of de Ugarte Postigo et al.
We apologise for the confusion caused by this rare glitch, which
coincided with the author's vacation (Murphy et al).
As ever, the most recent version of the position can be found online at:
https://www.swift.ac.uk/xrt_positions/01061482/
This circular is an official product of the Swift-XRT team.
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