TITLE:   GCN CIRCULAR
NUMBER:  30238
SUBJECT: GRB 210610B: REM optical/NIR observations of the afterglow
DATE:    21/06/15 18:34:17 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

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

We observed the field of GRB 210610B (Page et al., GCN Circ. 30170) with the REM 60cm robotic telescope located at the ESO premise of La Silla (Chile). 
The observations were performed starting  on 2021 June 10 at 23:14:12 UT (i.e. 3.38 hours after the burst) and were carried in the g, r, i, z, J, H and K bands. 

The optical/NIR afterglow (Page et al., GCN Circ. 30170) is detected with the following magnitudes: 

g = 17.48 +/-  0.10 
r = 17.02 +/-  0.06
i = 17.30  +/- 0.10
z = 16.13 +/-  0.15 (*)
(AB; calibrated against the Pan-STARRS catalogue)
(*): image affected by fringes

J = 15.94  +/- 0.23 
(Vega; calibrated against the 2MASS catalogue)

at a mid time of t-t0 = 4.01 hours.