TITLE: GCN CIRCULAR NUMBER: 15304 SUBJECT: GRB 131004A: optical afterglow from the NOT DATE: 13/10/04 22:44:30 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Xu, D. Malesani, J. Hjorth (DARK/NBI), P. Jakobsson (Univ. Iceland), T. Kruehler (ESO Santiago), Nicolaas Groeneboom, and Anders Hafreager (Univ. Oslo), report: We observed the field of GRB 131004A (Hagen et al., GCN 15303) using the NOT equipped with AlFOSC. Consistent with the XRT position, we detect a new source at coordinates: RA = 19:44:27.08 Dec = -02:57:30.2 The source is not visible in the DSS, and brighter than its limiting magnitude, hence it is very likely the afterglow of GRB 131004A. At a time of 0.43 hr after the GRB, we measure R = 20.2 +- 0.1 mag compared to nearby USNO-B1 R2 magnitudes, where the error is mostly due to calibration.