TITLE: GCN CIRCULAR NUMBER: 15471 SUBJECT: GRB 131108A: NOT optical observations DATE: 13/11/09 06:11:42 GMT FROM: Dong Xu at DARK/NBI D. Xu, D. Malesani (DARK/NBI), T. Pursimo (NOT) report on behalf of a larger collaboration: We observed the Swift/XRT field of Fermi-detected GRB 131108A (Racusin et al., GCN 15464; Stroh & Kennea, GCN 15468) using the 2.5m Nordic Optical Telescope (NOT) equipped with the MOSCA camera. We obtained SDSS ugriz frames, starting at 04:46:48 UT on 2013-11-09 (i.e., 8.081 hr after the Fermi/LAT trigger). The optical afterglow is detected at the border of the XRT error circle reported in Stroh & Kennea (GCN 15468) at coordinates R.A. (J2000) = 10:26:00.48 Dec. (J2000) = +09:39:44.05 Error Radius: ~0.5 arcsec thus being consistent with the XRT position, as reported in Gorosabel et al. (GCN 15469). In particular, the ugriz SED shows a clear drop at the wavelength range corresponding to the spectroscopic redshift of z=2.40 in de Ugarte Postigo et al. (GCN 15470).