GCN Circular 20638
K. E. Heintz (Univ. Iceland and DARK/NBI), D. Malesani (DARK/NBI and DTU Space), N. R. Tanvir (Univ. Leicester), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI), A. J. Korn (Uppsala Univ.) and I. R. Losada (NOT, NORDITA, and Stockholm Univ.) report on behalf of a larger collaboration: We observed the field of GRB 170208B (Siegel et al., GCN 20632) using the ALFOSC instrument equipped at the 2.56-m Nordic Optical Telescope (NOT). Observations started at 23:24:13.1 UT on 2017-02-08 (i.e., 50.5 min after the trigger). We obtained SDSS r- and z-band images with 3x300 s and 4x200 s exposures, respectively. The weather conditions were good with a measured seeing of 1.6 and 1.3 arcsec in the r- and z-band, respectively. In the stacked r- and z-bands no optical afterglow of the burst is detected within the XRT error circle (Goad et al., 20635) at limiting magnitudes of m(r) < 22.5 and m(z) < 22.2 (all AB) mag, calibrated with nearby stars from the Pan-STARRS survey.