TITLE: GCN CIRCULAR NUMBER: 21276 SUBJECT: GRB 170626A: TShAO optical observations DATE: 17/06/27 16:50:15 GMT FROM: Alexei Pozanenko at IKI A. Volnova (IKI), A. Pozanenko (IKI), I. Reva (Fesenkov Astrophysical Institute), E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 170626A (Marshall et al., GCN Circ. 21264; Hamburg & Meegan, GCN Circ. 21266) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on May 20 (UT) 18:42:38. We took several images in R-filter with total exposure of 1130 s. The optical afterglow (Moskvitin et al., GCN 21268; de Ugarte Postigo, et al., GCN 21269) is clearly visible in a stacked image. Preliminary photometry of the afterglow is following: Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) (3 sigma) 2016-06-26 16:47:33 0.30832 R 1130 19.87 0.13 21.0 The magnitude is also compatible with a magnitude of the afterglow reported by Lipunov (GCN 21272) after observation at the same epoch. Taken into account that between our observation at ~7.4 hours (mid time) and TNG observation at 11.53 hours (Melandri et al., GCN 21270) the magnitude of the aftegrlow did not change one may suggest either flare like activity or plateau phase of the afterglow and the burst can interesting for follow up observations. The finding chart can be found at http://grb.rssi.ru/GRB170626A/GRB170626a-fc_TShAO.png The photometry is based on nearby SDSS stars, part of them already used in Moskvitin et al. (GCN 21169). SDSS_id R_Lupton Err J110107.23 +564104.2 15.987 0.013 J110157.37 +563628.5 15.225 0.013 J110211.15 +563624.1 15.177 0.012 J110206.51 +563744.1 14.808 0.012 J110111.46 +563755.3 15.480 0.012 (GCN 21169) J110106.88 +563153.7 16.389 0.013 J110125.73 +563134.0 18.332 0.023 J110124.28 +563251.1 17.839 0.017