TITLE:   GCN CIRCULAR
NUMBER:  40895
SUBJECT: GRB 250702F: Ondrejov D50 optical afterglow detection
DATE:    25/07/02 21:46:43 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>

M. Jelinek, F. Novotny, A. Malenakova, J. Strobl, R. Hudec, C. Polasek (ASU CAS Ondrejov) report:We are observing the position of the Swift-detected GRB 250702F (trigger #1329888, very likely identical to Fermi GBM trigger #773183208) with the D50 robotic telescope of the Astronomical Institute Ondrejov, near Prague, Czech Republic. We initially performed a series of 20s unfiltered exposures starting 27.8s after the Swift trigger.
We clearly detect a possible optical afterglow in single 20s images at 14:11:44.6s +16:44:55 (J2000, 212.935979, +16.748483). The forward shock component peaked at unfiltered magnitude ~15.1 approximately 4 minutes post-GRB and shows a slow decay during our ongoing observations.
Further observations and detailed photometry are in progress.