[vsnet-grb-info 20846] GRB 180703A: optical afterglow confirmation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22944
SUBJECT: GRB 180703A: optical afterglow confirmation
DATE:    18/07/13 11:55:46 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi at fe.infn.it>

C. Guidorzi, R. Martone (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell 
(U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara, 
D. Morris (U. of Virgin Islands) on behalf of a large collaboration report:

We observed Fermi-LAT GRB 180703A (Racusin et al. GCN 22883) with the 
LCO 2-m unit in Hawaii (former FTN) on July 12, 17:46 UT (8.9 days after 
the GRB trigger time) with the SDSS i' filter. We do not detect the 
optical candidate (Guidorzi et al. GCN 22892) found on the border of the 
Swift-XRT error circle of the confirmed X-ray afterglow (Gibson et al. 
GCN 22931) down to a limit magnitude of i'> 22.0 with a 5x120s exposure. 
We therefore confirm the nature of optical afterglow of the candidate. A 
comparison between the images taken at both epochs is available at the 
link below.

http://www.fe.infn.it/u/guidorzi/new_guidorzi_files/180703A_OT.png