TITLE: GCN CIRCULAR NUMBER: 22059 SUBJECT: GRB 171027A: LCO 1-m telescope observations DATE: 17/10/27 11:51:22 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy 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 began observing Swift GRB171027A (D'Avanzo et al. GCN 22053) on October 27, from 08:39:29 to 09:06:37 UT (16 minutes since the GRB trigger time) with one of the 1-m LCO McDonald telescopes in the SDSS gri filters. Within the enhanced Swift-XRT error circle (Evans et al. 22054) and in particular at the position of the NIR afterglow candidate (Watson et al. GCN 22057) we do not see any optical source down to the following limits in agreement with previous reports (Lipunov et al. GCN 22055; Schady et al. GCN 22056): Mid Time���� Exposure������ Filter������ Magnitude (AB) (hrs)�������� (s) ------------------------------------------------------- 0.5��������� 5x60���������� SDSS-G��������� > 19.5 0.5��������� 5x60���������� SDSS-R��������� > 19.3 0.5��������� 5x60���������� SDSS-I��������� > 18.8 ------------------------------------------------------- as calibrated against nearby USNO URAT1 objects.