TITLE: GCN CIRCULAR NUMBER: 21333 SUBJECT: GRB 170711A: ISON/Terskol and AbAO optical observations DATE: 17/07/13 18:13:15 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), A. Pozanenko (IKI), A. Mokhnatkin (KIAM), R. Inasaridze (AbAO), E. Mazaeva (IKI), V. Agletdinov (KIAM), V. Ayvazian (AbAO), O. Kvaratskhelia (AbAO), G. Inasaridze (AbAO), I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 170711A (D'Elia et al. GCN 21321) with K-800 (0.8m) telescope of ISON/Terskol observatory starting on July, 12 (UT) 00:00:39 and AS-32 telescope of AbAO starting on July, 11 (UT) 23:58:46, i.e. about 1.6 hours after GRB trigger. We obtained several unfiltered images. We do not detect any source in stacked images within the enhanced XRT position (Beardmore et al. GCN 21323). Preliminary photometry of the field is following Date UT start t-T0 Filter Exp. OT Err. UL Telescope (mid, days) (s) 2017-07-11 23:58:46 0.07894 CR 11*60 n/d n/d 17.0 AS-32 2017-07-12 00:00:39 0.07658 CR 45*25 n/d n/d 19.1 K-800 Photometry is based on nearby stars of USNO-B1.0 USNO-B1.0_id R2 1378-0084355 14.59 1378-0084262 15.13 1378-0084218 14.70 We detect the object in coordinates (J2000) 03 03 11.46 +47 50 56.1 (+/- 0.5 arcsec) which is 7.7 arcsec apart from a center of the enhanced XRT position. The object is clearly detected in the stacked image of K-800 and marginally seen at the same position with AS-32 stacked image. The brightness of the object is 18.56 +/- 0.25 based on the reference stars listed above. The object is absent in the USNO-B1.0. At present, it is not clear whether this object has any relation to the GRB 170711A.