TITLE: GCN CIRCULAR NUMBER: 24265 SUBJECT: GRB 190427A: NOT optical observations DATE: 19/04/27 06:25:28 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst L. Izzo (HETH/IAA-CSIC), D. B. Malesani (DAWN/NBI and DARK/NBI), D. Xu (NAOC/CAS), and N. Jannsen (NOT), report: We observed the field of the Swift GRB 190427A (Tohuvavohu et al., GCN 24261; Campana et al., GCN 24264) using the Nordic Optical Telescope (NOT) located in La Palma (Canary Islands, Spain), equipped with the ALFOSC camera. We have obtained a series of 2 exposures of 300 s each in the SDSS r’, i’ and z’ filters. The first r'-band image was acquired starting on 2019 Apr 27.19742 UT (602 s after the GRB). Visual comparison with the Pan-STARRS archival images reveals no new sources inside the BAT error circle, down to a limiting magnitude r = 23.5 AB (calibrated against Pan-STARRS sources). Further analysis is ongoing.