TITLE: GCN CIRCULAR NUMBER: 18197 SUBJECT: GRB 150821A: LCOGT Sutherland observations DATE: 15/08/23 11:56:57 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana), C. Mundell (U. Bath) on behalf of a larger collaboration report: The 1-m LCOGT telescopes in Sutherland (South Africa) began observing Swift GRB 150821A (Troja et al. GCN 18186) on August 21, 19:39 UT (~9.9 hours after the burst trigger) with SDSS r and i filters. At the position of the optical afterglow (Troja et al. GCN 18186; D'Elia et al. GCN 18187; Kuin et al. GCN 18192; Kruehler et al. GCN 18195) we do not detect any source down to the following limits: Mid Time Exposure Filter Magnitude (hrs) (s) --------------------------------------------------- 10.4 2880 r' > 20.4 10.6 2880 i' > 21.0 --------------------------------------------------- Calibration is done against R2 and I values of USNOB-1 nearby stars.