TITLE: GCN CIRCULAR NUMBER: 27575 SUBJECT: GRB 200412B: Tautenburg observations DATE: 20/04/14 10:45:57 GMT FROM: Sylvio Klose at TLS Tautenburg S. Klose, B. Stecklum, S. Melnikov, and A. Nicuesa Guelbenzu (all Tautenburg) report: We continued observing the field of GRB 200412B (Fermi GBM team, GCN 27547) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6k x 6k CCD camera and the wide V-band filter (VB; Stecklum et al., GCN 27567). For the optical transient (Lipunov et al., GCN 27555, 27556) at a mean time APR 13, 21:08:59 UT (1.500 days post burst) we measure VB = 20.27 +/- 0.03. Compared to our 1st-epoch observations (dt=0.51 days; Stecklum et al., GCN 27567) this provides a decay slope of alpha = 1.58 (F\nu \propto t**(-\alpha)), in agreement with the results reported by Xin et al. (GCN 27571) and Belkin et al. (GCN 27574).