TITLE: GCN CIRCULAR NUMBER: 11419 SUBJECT: GRB 101112A: OSN and BTA observations DATE: 10/11/19 09:00:43 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia T. A. Fatkhullin, V. N. Komarova, V.V. Sokolov, A.S. Moskvitin (SAO-RAS), J. Gorosabel, A. Sota and A.J. Castro-Tirado (IAA-CSIC), A. de Ugarte Postigo (DARK/NBI), on behalf of a larger collaboration, report: "Following the detection of the optical afterglow to the INTEGRAL GRB 101112A (Gotz et al., GCNC 11396), we have undertaken observations of the region with the 1.5-m telescope at Sierra Nevada Obs. (Spain) on Nov 13 and with the 6.0-m BTA at SAO-RAS in Zelenchukskaia (Russia) on Nov 14 and Nov 15. At the location of the optical afterglow (Guidorzi et al., GCNC 11397, de Ugarte Postigo et al., GCNC 11398) a faint source with R-band magnitude about 23 was detected on Nov 14.766 UT, which was below the detection limit on Nov 15.838 UT. This value should be compared with R = 15.6, as derived from the BOOTES-2/TELMA early time images on Nov 12.9260 UT (a value that supersedes the one given on GCNC 11398 which was based on a wrong photometric calibration). The fact that the optical counterpart is blended (1."2) with a brighter star (with R about 18) has made useless the attempted spectroscopy on Nov 14.8 UT." This message can be quoted.