TITLE:   GCN CIRCULAR
NUMBER:  22507
SUBJECT: GRB 180316A: LCO Cerro Tololo observations
DATE:    18/03/16 12:10:56 GMT
FROM:    Renato Martone at Universita' di Ferrara  <mrtrnt@unife.it>

R. Martone, C. Guidorzi (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:

We observed the field of Swift GRB180316A (Melandri et al., GCN 22500) on March 16, from 07:38 to 07:59 UT (mid time of 0.12 days post burst) with a 1-m unit LCO telescope in Cerro Tololo in the SDSS r’ i' filters. We detect the optical afterglow (Lipunov et al., GCN 22502; Schady and Steinmassl, GCN 22504) with the following magnitudes:

Mid time since GRB     Exp        Filter         Magnitude
(days)                 (s)
-------------------------------------------------------------
0.11                   4x120      SDSS-R         19.04 +- 0.05
0.12                   4x120      SDSS-I         18.88 +- 0.05
-------------------------------------------------------------

as calibrated against nearby SDSS stars.