TITLE: GCN CIRCULAR NUMBER: 18618 SUBJECT: GRB 151118A: ISON-NM early optical limit DATE: 15/11/18 14:44:20 GMT FROM: Alexei Pozanenko at IKI, Moscow L. Elenin (KIAM), A. Volnova (IKI), E. Mazaeva (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 151118A (Amaral-Rogers et al., GCN 18611) with 0.4-m telescope of ISON-NM observatory in robotic mode starting on Nov., 18 (UT) 03:08:32 i.e. 122 seconds after burst trigger. We obtained 6 unfiltered images of 30 s exposure under unfavorable weather conditions. We do not detect any source within enhanced XRT error circle (Evans et al., GCN 18614): Date UT start t-T0 Filter Exp. UL(3 sigma) (mid, days) (s) 2015-11-28 03:08:32 0.00158 None 1*30 17.4 2015-11-28 03:08:32 0.00265 None 5*30 18.0 The photometry is based on nearby USNO-B1.0 stars: USNO-B1.0 id R2 1559-0079254 15.66 1558-0078601 16.03 1558-0078636 14.62