TITLE:   GCN CIRCULAR
NUMBER:  36078
SUBJECT: GRB 240411B: CrAO/ZTSh optical observations
DATE:    24/04/13 07:42:11 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>

 N. Pankov (HSE,IKI), V. Rumyantsev (CrAO), A. Pozanenko (IKI), S. Belkin
(IKI) report on behalf of IKI GRB FuN:

We observed the field of GRB 240411B (Parsotan et al., GCN 36063; Goad et
al., GCN 36065; D'Avanzo et al., GCN 36071; Lien et al., GCN 36072) with
ZTSh 2.6m telescope of CrAO observatory starting on 2024-04-11 (UT)
21:18:47. We detect optical afterglow (Izzo et al. GCN 36064; Schneider et
al. GCN 36067; Ror et al. GCN 36069; Ugarte Postigo et al. GCN 36074; Aryan
et al. GCN 36077).

Preliminary photometry of the afterglow in a combined image is following

Date UT start t-T0 Filter Exp. OT err UL(3sigma)
(mid, days) (s)
2024-04-11 21:18:47 0.283257 R 60*120 22.40 0.25 22.8

The photometry is based on several nearby USNO-B1.0 (R2) stars
USNO-B1.0