TITLE:   GCN CIRCULAR
NUMBER:  31471
SUBJECT: GRB 220101A: TSHAO optical observation, Terskol, AbAO upper limits
DATE:    22/01/17 22:02:27 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (HSE), A. Pozanenko (IKI), A. Kusakin (FAP), I. Reva (FAP), R. 
Ya. Inasaridze (AbAO), V. Agletdinov (KIAM), S. Belkin (IKI, HSE), I. 
Sokolov (KIAM), M. Krugov (FAP) 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),  Fermi/GBM (Lesage et al. 2022, GCN 31360), and 
Konus-Wind (Tsvetkova et al., GCN 31433)  with Zeiss-1000 telescope of 
THSAO observatory (Kazakhstan) in R-filter starting on 2022-01-05 (UT) 
14:39:20. We were also observing the afterglow position with with AS-32 
telescope of Abastumani observatory (AbAO) and K-800 telescope of Mnt. 
Terskol observatory on 2022-01-06.

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; 
Pankov et al., GCN 31398; Moskvitin et al., GCN 31420; Perley, GCN 
31425; Kumar et al., GCN 31442) is detected in THSAO observation, and 
upper limits obtained in Terskol K-800 and AbAO AS-32 observations.
Preliminary photometry of the afterglow and upper limits is following

Date UT start t-T0 Filter Exp. OT Err UL(3sigma) Telescope
2022-01-05 14:39:20 4.42129 R     25*180 22.19 0.23  22.5 Zeiss-1000
2022-01-06 15:06:30 5.45091 R    106*60  n/d   n/d   21.9 AS-32
2022-01-06 17:21:42 5.51841 Clear 30*60  n/d   n/d   21.5 K-800

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

Based on multiple observations cited above and our own observations the 
light curve in R-filter  can be approximated by a single power law 
(after one day after the trigger) with the power law index of -1.9. The 
light curve can be be found in
http://grb.rssi.ru/GRB220101A/GRB220101A_LC.png