S. Belkin (IKI), A. Pozanenko (IKI), V. Kim (FAI, Pulkovo Observatory),
R. Ya. Inasaridze (AbAO), E. Klunko (ISTP), M. Krugov (FAI), N.
Pankov (HSE), D. Datashvili (AbAO), V. R. Ayvazian (AbAO), G. V.
Kapanadze (AbAO) report on behalf of IKI GRB FuN:
We continued observation of the GRB 210807A (Lien et al., GCN 30600;
Ripa et al., GCN 30624) with AZT-20 of Assy observatory, AZT-33IK of
Mondy observatory, and AS-32 of Abastumani observatory.
The optical transient GRB 210807A (Lien et al., GCN 30600; Hu et al.,
GCN 30602; Lipunov et al., GCN 30607; Kim et al., GCNs 30614, 30616;
LaPorte et al., GCN 30618; Schmidl et al., GCN 30628) was detected in
almost all of our stacked images. Preliminary photometric results are
Date UT start t-T0 Filter Exp. OT Err. UL(3sig) Observ.
(mid, days) (s)
2021-08-07 23:46:09 0.58957 R 53*60 20.94 0.09 21.6 AbAO
2021-08-09 17:11:54 2.31822 R 30*120 22.6 0.35 22.5 Mondy
2021-08-10 17:22:17 3.32334 R 27*120 n/d n/d 22.7 Mondy
2021-08-10 21:33:07 3.50135 r(AB) 65*60 23.14 0.26 23.7 Assy
The photometry is based on the nearby stars of the USNO-B1.0 catalog.
and based on the same stars presented in PS1 catalog for r(AB) calibrations.
The light curve plotted based on available data for can be found at
The light curve can be approximated by broken power law with power law
indices of -0.55 and -1.05 before and after break at about 0.22 days.