TITLE: GCN CIRCULAR NUMBER: 11974 SUBJECT: GRB110422A: NOT optical follow-ups DATE: 11/04/25 21:46:49 GMT FROM: Dong Xu at Weizmann Inst Dong Xu (WIS), Erkki Kankare, Tuomas Kangas (U. Turku), and Pall Jakobsson (U. Iceland) report on behalf of a large collaboration: We continued to observe the field of GRB 110422A (Mangano et al., GCN 11957) at the Nordic Optical Telescope (NOT) equipped with ALFOSC. We obtained 2x360 s in the R filter with some clouds and a seeing ~0.9". The optical afterglow (Elunko et al., GCN 11958; Gres et al., GCN 11960; Xu et al., GCN 11961) has decayed to R=22.5+/-0.2 mag with a median time 21:17:58.8 UT on April 25 (i.e., 77.6 hr after the BAT trigger), calibrated with the #1651-0050630 star (R1=19.08) in the USNO B1 catalog.