GCN Circular 29846
A. Oksanen (Hankasalmi observatory) report on behalf a larger collaboration: We observed the field of the Swift GRB 210420B (Page et al., GCN 29844) using the 0.40 m remote controlled RC telescope of Hankasalmi observatory equipped with the SBIG STX-16803 CCD camera. Total of 25 exposures of 60 s each were secured in the clear filter, starting on 2021 April 19:44:58 UT. A candidate afterglow is clearly detected in the XRT error circle with coordinates (J2000): RA = 16:57:18.0 DEC = +42:34:12.6 Its magnitude is r = 17.97 +- 0.05 , calibrated against a nearby star from SDSS. This object is not visible in the Digitized Sky Survey R band images. We consider this object as a viable afterglow candidate to GRB 210420B, but a confirmation is necessary to assess variability. Further observations are planned.