TITLE:   GCN CIRCULAR
NUMBER:  31420
SUBJECT: GRB 220101A: SAO RAS optical observations
DATE:    22/01/09 14:22:05 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. S. Moskvitin (SAO), N. Pankov (HSE, IKI),  A. S. Medvedev (SAO), S. 
Belkin (IKI), A. Pozanenko (IKI)  report on behalf of GRB IKI FuN:

We observed Swift GRB 220101A (Tohuvavohu, et al., GCN 31347) also
detected by Fermi/LAT (Arimoto et al. 2022, GCN 31350), AGILE (Ursi et
al. 2022, GCN 31354), and Fermi/GBM (Lesage et al. 2022, GCN 31360) with 
Zeiss-1000 telescope of SAO RAS in Rc-filter starting on 2022-01-08 (UT) 
15:40:16.

We detected the afterglow (Tohuvavohu et al., GCN 31347; Kuin & 
Tohuvavohu, GCN 31351; Fu et al., GCN 31353; Hentunen et al., GCN
31356; Perley et al., GCN 31357; de Ugarte Postigo et al., GCN 31358;
Fynbo et al., GCN 31359; Vinko et al., GCN 31361; Tomasella et al., GCN
31363; Mao et al., GCN 31364; Noschese et al., GCN 31366; Mao et al., 
GCN 31368; Guelbenzu, et al., GCNs 31370, 31401; Strausbaugh et al., GCN 
31371; D'Avanzo et al., GCN 31373; Strausbaugh et al., GCNs 31383, 
31389; Dimple et al., GCN 31384; Romanov, GCN 31387; Caballero-Garcia, 
GCN 31388; Belkin et al., GCNs 31390, 31398; Gupta et al., GCN 31394; 
D'Avanzo et al., GCN 31395) in  a stacked image.

Preliminary photometry of the afterglow is following

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

2022-01-08 15:40:16   7.46534   Rc   16*300  22.8 0.3   23.2


The photometry is based on the nearby SDSS-DR12 stars
RA DEC R(Lupton transformations)
00:05:20.64408 +31:45:46.0728 18.562
00:05:34.81464 +31:45:50.5224 15.734
00:05:32.53944 +31:44:51.9396 15.369
00:05:36.69864 +31:44:42.4176 14.677