[vsnet-grb-info 20897] GRB 180721A: LCO Haleakala observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22995
SUBJECT: GRB 180721A: LCO Haleakala observations
DATE:    18/07/21 13:28:40 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:

The LCO 2-m unit at Haleakala Observatory (Hawaii) automatically began 
observing Swift GRB 180721A (Sbarufatti et al. GCN 22994) on July 21, 
11:21:40 UT (14.9 minutes after the GRB trigger time) with the SDSS i' 
filter. Within the Swift-XRT error circle we do not detect any source 
down to i'>20.2 mag at a mid time of 20.4 minutes post GRB with a 5x120s 
exposure, as calibrated against nearby SDSS objects.