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GCN Circular 40410

Subject

GRB 250509A: Prompt enhanced Swift-XRT position

Date

2025-05-09T23:32:52Z (3 days ago)

From

Phil Evans at U of Leicester <pae9@star.le.ac.uk>

Via

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using 426 s of promptly downlinked XRT event data for GRB 250509A, we
find an enhanced XRT position of the afterglow: RA, Dec: 46.44960,
-38.84128 which is equivalent to:
   RA (J2000)  = 03 05 47.90
   Dec (J2000) = -38 50 28.6
with an uncertainty of 1.9 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1311764.

Position enhancement is described by Goad et al. (2007, A&A, 476, 1401)
and Evans et al. (2009, MNRAS, 397, 1177).

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