TITLE: GCN CIRCULAR NUMBER: 22809 SUBJECT: GRB 180618A: TSHAO optical upper limit DATE: 18/06/20 17:57:39 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Kusakin (FAPHI), A. Pozanenko (IKI), I. Reva (FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB GRB 180618A (LaPorte et al., GCN 22790) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on June 18 (UT) 15:39:19. We obtained several images in R-filter. The optical afterglow (LaPorte et al., GCN 22790; Guidorzi et al., GCN 22792; Tyurina et al., GCN 22797) is not detected in a stacked image. Preliminary photometry of the field is following. Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2018-06-18 15:39:19 0.65209 R 36*120 n/d n/d 22.2 The photometry is based on several nearby SDSS-DR10 stars. Ref.stars SDSS_id R(Lupton) J112037.79+735136.8 17.37 J111905.28+734733.2 17.54 J111907.19+734657.8 17.04