TITLE: GCN CIRCULAR NUMBER: 16656 SUBJECT: GRB 140801A: NOT afterglow confirmation DATE: 14/08/02 03:34:21 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), S. Schulze (PUC, MAS), M. El-Souri, S. Boye Nissen, M. Sparre, J. P. U. Fynbo (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), P. Jakobsson (U. Iceland) report on behalf a larger collaboration: We observed the field of GRB 140801A (Fermi trigger 428612396) with the 2.5-m Nordic Optical Telescope (NOT) equipped with ALFOSC. We obtained a 200-s exposure in each of V, R, and I bands. Observations started at 01:07:23 UT on August 2 (i.e. 6.12 hours after the burst). The optical transient reported by Gorbovskoy et al. (GCN 16653) is clearly detected in each of our images at the same position. And it has decayed to R(Vega) ~ 20.6 mag at 6.15 hours post-trigger, calibrated against two bright nearby USNO B1 stars. This measurement is not corrected for foreground extinction. The OT roughly decays as t^-1.5 during the MASTER observations (GCN 16653), and then changes to roughly as t^-0.9 assuming a simple power-law decline since the MASTER's end-time. The whole behavior is similar to that of previous GRB optical afterglows. We thus conclude that this OT is very likely the optical afterglow of GRB 140801A.