TITLE: GCN CIRCULAR NUMBER: 39527 SUBJECT: EP250228a: Swift/XRT localisation DATE: 25/02/28 10:52:50 GMT FROM: K.L. Page at U Leicester klp5@leicester.ac.uk

K.L. Page, P.A. Evans (U.Leicester) and J. DeLaunay (PSU) report on behalf of the Swift XRT Team:

On 2025 February 28, at 05:53 UT, Swift obtained an Target of Opportunity observation of EP250228a (GCN Circ. 39525), collecting ~340 s of data around 1.9 hr after the Einstein Probe trigger. The XRT data show an uncatalogued X-ray source, consistent with the FXT source reported by the EP team, at a position of RA, Dec = 103.60631, -41.57160, which is equivalent to

RA (J2000): 06h 54m 25.51s Dec (J2000): -41d 34′ 17.8″

with an uncertainty of 4.4 arcsec (radius, 90% confidence). The flux of this source was (5.4 +/- 0.9) x 10^-12 erg cm^-2 s^-1 (0.3 - 10 keV).

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