[vsnet-grb-info 27198] GRB 210112A: 1.3m DFOT Optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29301
SUBJECT: GRB 210112A: 1.3m DFOT Optical upper limit
DATE:    21/01/13 19:54:17 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157 at gmail.com>

Rahul Gupta (ARIES),  Amit Kumar (ARIES), Dimple (ARIES), Ankur Ghosh
(ARIES), Krishan Chand (ARIES), Amar Aryan (ARIES), Shashi B. Pandey
(ARIES), and Kuntal Misra (ARIES) report:


We observed the filed of Swift and AGILE detected GRB 210112A (Ambrosi
et al., GCN 29289; and Ursi et al., GCN 29293) with 1.3m Devasthal
Fast Optical Telescope (DFOT) located at Devasthal observatory of
Aryabhatta Research Institute of Observational Sciences (ARIES),
India. The observations were started on 2021-01-13 at 00:06:18 UT i.e.
~ 22.49 hours after the BAT trigger. We have taken multiple frames
having an exposure time of 120 s in the R filter. We do not detect the
optical afterglow candidate (Ambrosi et al., GCN 29289; and Kann et
al., GCN 29296) within enhanced Swift-XRT position (Goad et al., GCN
29290).


We obtain the following 3-sigma upper limits in the stacked image.


Date Start_UT    T_start-T0 (hrs)        Filter   Exp time (s)
Limiting Magnitude

============================================================
2021-01-13   00:18:18      22.69              R              120*12
           > 22.0



The magnitude is not corrected for the Galactic extinction in the
direction of the burst. Photometric calibration is performed using the
standard stars from the USNO-B1.0 catalogue.

This circular may be cited.