TITLE:   GCN CIRCULAR
NUMBER:  30288
SUBJECT: GRB 210619B: REM optical/NIR afterglow detection
DATE:    21/06/21 13:00:05 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 210619B (D'Avanzo et al., GCN Circ. 30261) with the REM 60cm robotic telescope 
located at the ESO premise of La Silla (Chile). The observations were carried in the g, r, i, z, J, H and K bands, starting 
on 2021 June 20 at 06:07:59 UT (i.e. 6.14 hours after the burst) and lasting for about one hour. 

The optical/NIR afterglow (D'Avanzo et al., GCN Circ. 30261) is detected in all bands. From preliminary photometry we 
derive the following magnitudes: 

r = 18.52 +/-  0.12
(AB; calibrated against the Pan-STARRS catalogue)

J = 17.10  +/- 0.24 
H = 16.61  +/- 0.25 
K = 15.13  +/- 0.23 
(Vega; calibrated against the 2MASS catalogue)

at a mid time of t-t0 = 6.3 hours.