TITLE:   GCN CIRCULAR
NUMBER:  23021
SUBJECT: GRB 180720B: REM photometry
DATE:    18/07/23 09:43:43 GMT
FROM:    Stefano Covino at Brera Astronomical Observatory  <stefano.covino@gmail.com>

S.Covino, D. Fugazza (INAF/OAB), on behalf of the REM team, report:

We observed the field of GRB180720B (Siegel et al. GCN 22973) with the REM 60cm robotic telescope located at the ESO premise of La Silla (Chile).
The observations were performed starting from about 13.5 hours after the event and were carried in the g, r, i, z, J, H and K bands. 

The optical counterpart (Martone et al. GCN 22976) is still detected in the optical and in the NIR bands. A preliminary photometry on the first H band set of frame gives:

H = 15.65 +- 0.22 at 13.7 hours from the GRB time.

Magnitudes are calibrated against the 2MASS catalogue.