GCN Circular 29498

K. E. Heintz (Univ. of Iceland), D. B. Malesani (DTU space), L. Izzo (DARK/NBI), and A. A. Djupvik (NOT), report on behalf of a larger collaboration:

We observed the field of GRB 210212A (Troja et al., GCN #29487), using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Starting at 20:05:37 UTC on February 12, i.e. 15.5 hr after trigger, we obtained 3x600s exposures in the r-band. The observations were carried out under good conditions, with seeing around 0.8".

Within the refined Swift/XRT error circle (Beardmore et al., GCN #29489), we detect a faint, extended source with FWHM = 1.5". We measure r = 23.23 +/- 0.12 mag, calibrated against nearby field stars in the Pan-STARRS DR1 catalog. At the same position, we also tentatively detect a source in archival Pan-STARRS images.

This source is potentially the host galaxy of GRB 210212A. However, due to the relatively large uncertainty of the currently available XRT position (3.6"), we estimate a chance probability for this source to be unrelated to the GRB of P = 0.09 based on the formalism by Bloom et al. (2002, AJ, 123, 1111).