TITLE: GCN CIRCULAR NUMBER: 39960 SUBJECT: GRB 250331C: Prompt enhanced Swift-XRT position DATE: 25/03/31 05:45:04 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk

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

Using 1.6 ks of promptly downlinked XRT event data for GRB 250331C, we find an enhanced XRT position of the afterglow: RA, Dec: 80.95640, 33.06317 which is equivalent to: RA (J2000) = 05 23 49.54 Dec (J2000) = +33 03 47.4 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/1299967.

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.

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