[vsnet-grb-info 26383] Improved enhanced Swift-XRT position of GRB 200922A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28483
SUBJECT: Improved enhanced Swift-XRT position of GRB 200922A
DATE:    20/09/23 13:11:07 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at leicester.ac.uk>

P.A. Evans (U. Leicester), A. D’ai (INAF-IASFPA) and M. J. Moss (GWU)
report on behalf of the Swift-XRT team:

The enhanced-XRT position reported in GCN Circ. 28473 was a particularly poor
position and has been improved and shifted by the receipt of further data, as
noted by Izzo et al (GCN. Circ. 28478).

The best XRT position, available at
https://www.swift.ac.uk/xrt_positions/00997024/ is RA, Dec = 296.95364,
-55.20442 degrees which is equivalent to:

RA (J2000)  = 19h 47m 48.87s
Dec (J2000)  = -55d 12' 15.9”

with an uncertainty of 1.5” (radius, 90% confidence). This position is
consistent with the source seen by UVOT and LCO (GCN Circs. 28471, 28478).

It is normal for the XRT position to evolve slightly as new data are received, with
the website always being the source of the most recent position. In the case of
this GRB, the first visibility window for Swift was very short, and the
satellite attitude appears to have been less stable than usual; this resulted in
the position in GCN 28473 being unusually inaccurate.

This circular is an official product of the Swift-XRT team.