TITLE:   GCN CIRCULAR
NUMBER:  21270
SUBJECT: GRB 170626A: TNG optical observations
DATE:    17/06/26 22:28:12 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

A. Melandri, P. D'Avanzo (INAF-OAB), V. D'Elia (INAF/OAR & ASI/ASDC), D. Carosati, G. Andreuzzi (INAF-TNG) report on behalf of the CIBO collaboration: 

We observed the field of GRB 170626A (Marshall et al., GCN Circ. 21264; Hamburg & Meegan, GCN Circ. 21266) with the 3.6m Telescopio Nazionale Galileo (TNG) equipped with DOLoRes. Observations were carried out in the r-sdss filter. Observations started on Jun 26 at 21:07:35 UT (~11.53 hours after the burst) and consist in a single image lasting 180 seconds.

At the edge of the refined XRT position (Cholden-Brown et al., GCN Circ. 21267) we detect a candidate optical afterglow at the following coordinates: RA(J2000) = 11:01:34.04, Dec(J2000) = +56:28:35.0, with an uncertainty of 0.5". This position is in agreement with the one reported by Moskvitin (GCN Circ. 21268).

The optical afterglow is detected with a magnitude r(AB) = 20.2 +/- 0.2 (calibrated against nearby stars reported in the PAN-STARSS catalogue).