TITLE:   GCN CIRCULAR
NUMBER:  35691
SUBJECT: GRB 240204A: Mondy optical afterglow observations
DATE:    24/02/06 07:50:17 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

S. Belkin (IKI, HSE), N. Pankov (HSE, IKI), E. Klunko (ISTP), A. Pozanenko (IKI)  report on behalf of IKI-GRB-FuN:

We observed the GRB 240204A  (Fermi-GBM team GCN 35664, Cenko et al. GCN 35666, Pozanenko et al. GCN 35670, Leonini et al. GCN 35672, Pérez-Fournon et al. GCN 35673, Dainotti et al. GCN 35677, Bochenek et al. GCN 35678; Adami et al. GCN 35690)  with AZT-33IK telescope of Mondy observatory  starting on 2024-02-04 (UT) 16:05:26 and  2024-02-05 (UT) 13:10:09. Preliminary photometry of the afterglow  based on USNO-B1.0 (R2) nearby stars is following

Date  UT start t-T0  Filter Exp. OT Err. UL(3sigma)
    (mid, days)  (s)

2024-02-04 16:05:26  0.04292 R 480  19.90 0.10 21.9
2024-02-04 16:13:26  0.04847 R 480  20.01 0.11 21.8
2024-02-04 16:21:26  0.05403 R 480  19.93 0.10 21.9
2024-02-04 16:29:27  0.05959 R 480  19.85 0.09 21.8
2024-02-04 17:31:00  0.11345 R 2400 20.55 0.10 22.5
2024-02-05 13:10:09  0.96772 R 8400 22.4  0.2  23.1