[vsnet-grb-info 20893] GRB 180720C: LT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22991
SUBJECT: GRB 180720C: LT observations
DATE:    18/07/21 08:22:42 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) on behalf of a 
large collaboration report:

The 2-m robotic Liverpool Telescope automatically began observing Swift 
GRB 180720C (LaPorte et al. GCN 22982) on July 20, 22:28:18 UT (261 
seconds after the GRB trigger time) with the RINGO3 polarimeter and the 
IO:O camera in the SDSS-R filter. Within the enhanced Swift-XRT error 
circle (Evans et al. GCN 22987) we do not find any uncatalogued object 
down to r'>20.4 mag at a mid time of 47 minutes post GRB with a 3x10s 
exposure, as calibrated against nearby Pan-STARRS objects.