[vsnet-grb-info 21101] GRB 180904A: LT early observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23199
SUBJECT: GRB 180904A: LT early observations
DATE:    18/09/05 09:57:11 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 180904A (D'Ai et al. GCN 23194) with the polarimeter RINGO3 and the 
IO:O camera on September 04, 21:32:12 UT (219 seconds from the GRB 
trigger time). Within the enhanced Swift-XRT error circle (Osborne et 
al. GCN 23196) we do not detect any object down to a limit of r' > 21.2 
mag in a 6x10s exposure at a mid time of 37 minutes post burst, as 
calibrated against nearby Pan-STARRS objects, in agreement with previous 
reports (Malesani et al. GCN 23195; Izzo et al. GCN 23197; Moskvitin et 
al. GCN 23198).