GCN Circular 23478
Kasper E. Heintz (Univ. of Iceland), Daniele B. Malesani (DAWN/NBI and DARK/NBI), and Shane Moran-Kelly (Univ. of Turku and NOT), report on behalf of a larger collaboration: We observed the optical afterglow (Podesta et al., GCN 23470; Kong, GCN 23475; Lipunov et al., GCN 23476: Volnova et al., GCN 23477) of the INTEGRAL GRB 181201A (Mereghetti et al., GCN 23469) with the 2.5-m Nordic Optical Telescope (NOT) equipped with StanCam. Observations were carried out in the Bessel R filter, but calibrated against SDSS r-band Pan-STARRS local photometry, corrected to the R-band using the Lupton transformation. At a mid-time of 20:27:09 UT on December 1 (i.e. 17.8 hr after trigger) we measure for the optical counterpart: r = 17.5 +/- 0.1 AB mag, where the error is dominated by scatter in the preliminary calibration.