TITLE:   GCN CIRCULAR
NUMBER:  21372
SUBJECT: GRB 170728B: TNG optical afterglow candidate
DATE:    17/07/29 01:16:51 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo (INAF-OAB), V. D'Elia (INAF/OAR & ASI/ASDC), M. Cecconi, H. Stoev (INAF-TNG) 
report on behalf of the CIBO collaboration: 

We observed the field of the short GRB 170728B (Cenko et al., GCN Circ. 21371) with the 3.6m 
Telescopio Nazionale Galileo (TNG) equipped with DOLoRes. Observations were carried out in 
the r-sdss filter. Observations started Jul 28 at 23:55:49 UT (~52.5 minutes after the burst) and 
consist in a single image lasting 300 seconds.

Inside the enhanced XRT position (http://www.swift.ac.uk/xrt_positions/) we detect a candidate optical 
afterglow. From preliminary photometry we estimate a magnitude r(AB)~20.6 (calibrated against nearby 
stars reported in the PAN-STARSS catalogue).