GCN Circular 45252
Subject
EP260727a: SAO RAS optical observations
Event
Date
2026-07-29T12:55:38Z (3 days ago)
From
Alexander Moskvitin at SAO RAS <mosk@sao.ru>
Via
email
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.