TITLE: GCN CIRCULAR NUMBER: 22711 SUBJECT: GRB 180512A: Upper limits from OSN DATE: 18/05/12 23:37:11 GMT FROM: Alexander Kann at IAA-CSIC A. de Ugarte Postigo (HETH/IAA-CSIC, Dark/NBI), L. Izzo, D. A. Kann (both HETH/IAA-CSIC), and A. Sota (IAA/CSIC) report on behalf of HETH: We observed the field of GRB 180512A (Deich et al.; GCN Circ. 22710) with the 1.5-m OSN telescope in Granada, Spain Observations started at 22:15:35 UT (827 s after the GRB trigger) for OSN, and we obtained 8x60s images in the Rc band and 6x300s images in the Ic band. Observations were obtained in inclement conditions (bad seeing of ~3"). In our stacked images, we find no source inside the Swift-XRT error circle down to a 3-sigma limit of Ic (Vega) > 21. The calibration was performed using nearby stars in the SDSS catalog.