TITLE:   GCN CIRCULAR
NUMBER:  31821
SUBJECT: GRB 220403B: optical detection by D50
DATE:    22/04/03 22:14:20 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

M. Jelinek, J. Strobl, R. Hudec, C. Polasek (ASU CAS Ondrejov) report:

We observed the position of the Swift-detected GRB 220403B (Klingler et
al. GCNC 31820) with the D50 telescope of the Astronomical Institute
Ondrejov, near Prague, Czech Republic. Our observation started at 21:04 UT,
i.e. 22 min after the initial trigger and was performed without a filter.

We detect the optical afterglow (Klingler et al. GCNC 31820) in a combined
image with exp. mean time 31.3 min after trigger (exposed 21:05--21:22UT)
with an AB magnitude RC = 19.02 +/- 0.04.