TITLE: GCN CIRCULAR NUMBER: 35382 SUBJECT: GRB 231216A: NOT optical upper limits DATE: 23/12/16 22:12:21 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl> Daniele B. Malesani (DAWN/NBI and Radboud Univ.), Jacco H. Terwel (TCD and NOT), Benjamin N. Hauptmann (DTU Space and NOT) report on behalf of a larger collaboration: We observed the position of GRB 231216A (Sbarrato et al., GCN 35378) using the Nordic Optical Telescope equipped with the ALFOSC images. Observations were carried out in the SDSS r and z filters, with an exposure time of 4x200 s in each filter. The delivered seeing in the combined images was around 1.5", and some calima affected the sky transparency. Within (or near) the current XRT error circle, we detect no new objects down to magnitudes r > 23.5 and z > 21.5 (both AB), with mean times 2.25 and 2.44 hr after the trigger, respectively. View this GCN Circular online at https://gcn.nasa.gov/circulars/35382. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...