TITLE:   GCN CIRCULAR
NUMBER:  29148
SUBJECT: GRB 201221D: 3.6m DOT optical observations
DATE:    20/12/23 12:27:46 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157@gmail.com>

Dimple (ARIES), A. Panchal (ARIES), A. Gangopadhyay (ARIES), A. Ghosh
(ARIES), R. Gupta (ARIES), A. Kumar (ARIES), K. Misra (ARIES), and S. B.
Pandey (ARIES) report:

We carried out the follow-up observations of GRB 201221D (Page et al., GCN
29112) with Aries Devasthal Faint Object Spectrograph and Camera (ADFOSC)
mounted on the 3.6m Devasthal Optical Telescope (DOT) at Devasthal
observatory of Aryabhatta Research Institute of observational sciencES
(ARIES), India. The observations were started on 2020-12-22 at 23:10:00 UT.
We observed a series of 4 images with the exposure time of 900 seconds each
in r-band. At the position reported by Malesani et al., (GCN 29117), we
detect an uncatalogued source in r-band with a magnitude of 23.46 +- 0.09
(AB mag), calibrated with the nearby PanSTARRS field. However, we remark
that this is an extended source and may contain significant host galaxy
contribution. For further verification, host galaxy subtraction is highly
encouraged.

The magnitude is not corrected for the Galactic extinction in the direction
of the burst.

This circular may be cited.