TITLE: GCN CIRCULAR NUMBER: 39281 SUBJECT: EP250207b: Liverpool Telescope possible optical counterpart DATE: 25/02/11 10:20:29 GMT FROM: Rob Eyles-Ferris at U of Leicester raje1@leicester.ac.uk
R. A. J. Eyles-Ferris, P. T. O’Brien and R. L. C. Starling (U of Leicester) report:
We observed the field of the X-ray transient EP250207b (Zhou et al., GCN 39266) using the IO:O on the 2m Liverpool Telescope. We obtained 5x90s exposures in the SDSS g’ filter starting at 2025-02-10 00:49:54 UT and 5x90s exposures in the SDSS r’ filter starting at 2025-02-10 00:59:10 UT, approximately 74 hours after the X-ray detection.
We performed image subtraction on the stacked images using reference images from Pan-STARRS. We identify a possible counterpart in the g’ band subtraction of g’ = 21.24+/-0.14 with photometry calibrated to Pan-STARRS and not corrected for Galactic extinction. The source is located at RA, Dec = 167.51128, -7.87019 deg, which is equivalent to: RA (J2000) : 11:10:02.71 Dec (J2000): -07:52:12.7
This source lies within the error region of the Einstein Probe FXT detection and is the only source within it in our subtracted image. It is consistent with the position of the bright galaxy noted by Malesani et al., GCN 39270 and Levan et al., GCN 39278 with an offset of 0.92 arcsec (1.43 kpc projected) from the position reported by Malesani et al., GCN 39270.
In the r’ band subtraction, the source position is obscured by a subtraction artifact and we cannot currently rule out the possibility that the g’ band detection is also an artifact. Further observations to confirm the nature of the source are planned.
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