GCN Circular 30670
Subject
GRB 210820A: NOT optical upper limit
Date
2021-08-21T07:30:12Z (3 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Z.P. Zhu (NAOC, HUST), D. B. Malesani (DTU space), L. Izzo (DARK/NBI),
J.P.U. Fynbo (DAWN/NBI), D. Xu (NAOC), R. Clavero (NOT) report on behalf
of a larger collaboration:
We observed the field of GRB210820A (Beardmore et al., GCN30664) using
the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. We
obtained 3x200s frames in the Sloan r- filter, starting at 00:49:56 UT
on 2021-08-21 (i.e., ~ 7.29 hr after the BAT trigger).
No optical source is detected in our stacked image at the Swift/UVOT
position (Beardmore et al., GCN 30664), down to a limiting magnitude of
r~22.2, calibrated with the nearby PanSTARRS field.