TITLE: GCN CIRCULAR NUMBER: 41483 SUBJECT: GRB 250821A: NOT z-band upper limit DATE: 25/08/22 02:33:46 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk> M. Beyer Stjerne (KU), K. A. Grimstrup (KU), W. K. Krarup Mirsal (KU), C. Lind-Thomsen (KU), F. Hjorth Gammelgaard (KU), I. L. Róbertsdóttir (KU), J. P. U. Fynbo (DAWN/NBI), K. Valeckas (NOT and KU), R. Holmberg Rasmussen (NOT and Aarhus), D. B. Malesani (DAWN/NBI) and Radboud), report on behalf of a larger collaboration: We observed the field of the Swift GRB 250821A (Dichiara et al., GCN 41462) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. A total of 45 min of imaging was secured using the SDSS z filter, with a mean epoch 2025 Aug 22.075 UT (15.0 hr after the Swift/BAT trigger). No new sources are detected consistent with the Swift/XRT position (Beardmore et al., GCN 41472), down to a 3-sigma limit of z > 22.8 (AB), calibrated against nearby stars from the Pan-STARRS catalog. Our result is consistent with, and extends to redder wavelengths, the non-detections reported by Strausbaugh & Cucchiara (GCN 41466) and Oates & Dichiara (GCN 41471). View this GCN Circular online at https://gcn.nasa.gov/circulars/41483. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...