TITLE:   GCN CIRCULAR
NUMBER:  31356
SUBJECT: GRB 220101A: THO optical observations
DATE:    22/01/01 21:29:30 GMT
FROM:    Veli-Pekka Hentunen at Taurus Hill Obs,A95  <veli-pekka.hentunen@kassiopeia.net>

Veli-Pekka Hentunen, Markku Nissinen and Esa Heikkinen (Taurus Hill
Observatory, Varkaus, Finland) report:

We have detected GRB 220101A optical afterglow at Taurus Hill 
Observatory (A95) using Meade 16" ACF 0.40-m/f8.0 telescope 
and ASI2600MM Pro CMOS camera. We used Chroma Bessell 
photometric VRI filters. The observations were started at 2022-01-01 
14:40 (UT).

The optical afterglow was detected at the position RA 00:05:24.8 
and DEC +31:46:09.7.

The following magnitudes were obtained from the observations using 
USNO-B1.0 1217-1802 (V=15.29, R=14.70, I=14.74) as a comparison star:

Tmid(h)+T0   	Filter	Exp. time    Mag	Mag. Err.   	
9.733		V	300s	>18.7	
9.994		I	300s	17.91	0.08
10.168		R	300s	19.26	0.13
10.661		I	3x300s	18.08	0.10
10.835		R	3x300s	19.16	0.13

URL-link to our image: 
https://www.kassiopeia.net/wp-content/uploads/2022/01/grb220101a_I2_nega_web.jpg