TITLE:   GCN CIRCULAR
NUMBER:  29567
SUBJECT: GRB 210222B: REM observations of the optical/NIR afterglow
DATE:    21/02/25 21:29:46 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo, S. Covino, D. Fugazza, A. Melandri (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 210222B (Gropp et al., GCN Circ. 29545) with the REM 60cm robotic telescope 
located at the ESO premise of La Silla (Chile). The observations were performed starting  on 2021 February 23 
at 00:18:20 UT (i.e. 1.68 hours after the burst) and were carried in the g, r, i, z, J and H bands. 

The optical afterglow (Gropp et al., GCN Circ. 29545) is detected in all bands. 

From preliminary photometry we obtain for the optical/NIR afterglow the following magnitudes:

r = 18.85 +/- 0.13 (AB; calibrated against the Pan-STARRS catalogue)
H = 16.39 +/- 0.20 (Vega; calibrated against the 2MASS catalogue)

at a mid time of t-t0 = 1.93 hours.