TITLE: GCN CIRCULAR NUMBER: 45252 SUBJECT: EP260727a: SAO RAS optical observations DATE: 26/07/29 12:55:38 GMT FROM: Alexander Moskvitin at SAO RAS <mosk@sao.ru> A. Moskvitin (SAO RAS), A. Pozanenko (IKI), N. Pankov (IKI) report on behalf of GRB follow-up team We observed the field of EP260727a (Hu et al., GCN 45235)  with the Zeiss-1000 1-m telescope of SAO RAS equipped  with the CCD photometer. We obtained 9*20 + 4*300 sec. images  with Rc filter from 2026-07-27T23:31:14 to 2026-07-28T00:07:51 under mediocre weather conditions and seeing of 3".3. The OT (He et al., GCN 45234; Eyles-Ferris et al., GCN 45239; Adami et al., GCN 45243; Guziy  et al., GCN 45245; also consistent  with the EP-FXT position, Wu et al., GCN 45244) is clearly detected  in the stacked image with the following brightness. Date        UTstart  t-T0     Exp.   Filter Mag    Err.    UL                     (mid, h) (n*s)                      (3-sigma)                     2026-07-27  23:31:14  3.1932  1380   Rc     21.64 +/- 0.17  22.5     Near the position of the second candidate proposed by Adami et al.,  (GCN 45243) we note the presence of an extended source  with the coordinates (J2000.0) R. A. = 23:05:48.72; Dec. = +03:15:23.5 and brightness of R = 21.55 +/- 0.11. This preliminary photometry was given in the Vega system, calibrated  against nearby SDSS stars (magnitudes converted with Lupton 2005  equations) and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/45252. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...