TITLE: GCN CIRCULAR NUMBER: 38910 SUBJECT: EP250111a: Swift/XRT detection and fading DATE: 25/01/11 14:46:54 GMT FROM: Jamie Kennea at Penn State jak51@psu.edu

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

At 04:08UT on January 9th, 2025 Swift began a 1.7ks target-of-opportunity observation of the Einstein Probe discovered transient EP250111a (GCN #38905), approximately 2.8 hours after the EP trigger. XRT detects a previously uncatalogued point source at the following coordinates: RA/Dec(J2000) = 97.17996, +56.8970, which is equivalent to:

RA(J2000) = 06h 28m 43.19s Dec(J2000) = +56° 53′ 49.1″

with an estimated uncertainty of 5.8 arc-seconds radius (90% confidence). This position lies 5 arc-seconds from the reported localization by the EP FXT reported in GCN #38905. This position lies 5.6 arc-seconds from the reported NOT optical candidate (GCN #38906).

The X-ray flux of this source is 3.9(+1.4/-1.1) x 10^-13 erg/s/cm^2 (0.3-10 keV), approximately an order of magnitude fainter than the FXT flux.

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