TITLE:   GCN CIRCULAR
NUMBER:  46271
SUBJECT: GRB 261113A: Ondrejov D50 optical observations
DATE:    26/11/14 12:25:30 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>

M. Jelinek, J. Strobl, F. Novotny and R. Hudec (ASU CAS Ondrejov) report:

We observed the optical afterglow of the SVOM/ECLAIRs GRB 261113A (Saccardi
et al., GCN 46244; Lin et al., GCN 46247) with the D50 telescope of the
Astronomical Institute Ondrejov, near Prague, Czech Republic. Our
observations started at 16:48 UT on 2026 November 13, i.e. ~2.3 h after the
trigger, and continued until 22:17 UT, cycling through the SDSS r, g and
i filters.

The afterglow is detected in all filters. In the first combined r-band
image (mean time ~2.7 h after the trigger) we measure r = 20.51 +/- 0.09
(AB, calibrated against ATLAS-RefCat2, not corrected for Galactic
extinction).

Our multicolour sequence follows the afterglow decay up to ~7.8 h after
the trigger. The analysis is ongoing.