TITLE: GCN CIRCULAR NUMBER: 20579 SUBJECT: GRB 170202A: LCO Sutherland observations DATE: 17/02/02 22:32:33 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large collaboration report: We observed Swift GRB 170202A (Racusin et al. GCN 20575) on February 02, from 21:19 UT (2.8 hours since the GRB) with 1-m LCO telescope units in Sutherland with SDSS r and i filters. We detect the optical afterglow (Racusin et al. GCN 20575; Xi et al. GCN 20576; Lipunov et al. GCN 20578) at the Swift-UVOT position with the following values: Mid Time Exposure Filter Magnitude (AB) (hours) (s) ------------------------------------------------------- 2.9 4x120 SDSS-R 19.65 +- 0.15 3.0 4x120 SDSS-I 19.32 +- 0.18 ------------------------------------------------------- as calibrated against nearby SDSS sources.