TITLE:   GCN CIRCULAR
NUMBER:  21825
SUBJECT: GRB 170906A: REM optical/NIR observations
DATE:    17/09/06 07:08:29 GMT
FROM:    Stefano Covino at Brera Astronomical Observatory  <stefano.covino@brera.inaf.it>

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

We observed the field of the GRB 170906A (Siegel et al., GCN 21821) with the 60-cm robotic 
telescope REM located at the La Silla Observatory (Chile).  The observations started at 00:44:23 UT, 
about 72 s after the burst, and were carried out simultaneously in the g, r, i, z and H bands.

A preliminary analysis shows that the optical counterpart reported by UVOT (Siegel et al., GCN 21821)
is well detected in all bands and between 2 and 3min after the burst it was:

r = 13.10 +- 0.10 (AB)
H = 12.00 +/- 0.05 (Vega)

Magnitudes are calibrated against the 2MASS catalog in the NIR and the APASS catalogue for the optical.