GCN Circular 18097
E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 150728A (Krimm et al. GCN 18087) with Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory starting on Jul. 29 (UT) 18:34:50. We obtained several images in R-filter. In a combined image we do not detect the FTN object (Dichiara et al. GCN 18090) also visible in AAO observations (Mazaeva et al., GCN 18094) and source A in RATIR observations (Watson et al., GCN 18096). A photometry of the field is following Date UT start t-T0 Filter Exp. ULimit (3sigma) (mid, days) (s) 2015-07-29 18:34:50 1.26425 R 15*300 21.2 The photometry is based on nearby USNO-B1.0 stars USNO-B.1_id R2 1239-0338943 17.06 1239-0338998 16.69 Also we marginally detect object B of the RATIR observations (Watson et al., GCN 18096) in our current and previous observation of the field (Mazaeva et al., GCN 18094). The finding chart can be found in http://grb.rssi.ru/GRB150728A/GRB150728A_AAO_left_TSHAO_right.png Would the source A be a non-variable point like object with magnitudes of r=21.37+/-0.04 and i=20.89+/-0.04 (Watson et al., GCN 18096) in our observation the object A might be detected as the object with a magnitude less than R=21.3 (3 sigma). So we tentatively suggest the object A as an afterglow candidate.