[vsnet-grb-info 27415] GRB 210208A: 1.3m DFOT Optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29518
SUBJECT: GRB 210208A: 1.3m DFOT Optical upper limit
DATE:    21/02/17 19:26:19 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157 at gmail.com>

Rahul Gupta,  A. Kumar, Dimple,  A. Ghosh, A. Aryan, B. Kumar, S. B.
Pandey, and K. Misra (ARIES) report:

We observed the field of INTEGRAL detected GRB 210208A (Mereghetti et
al., GCN 29429) 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 2021-02-13 at 22:43:42 UT i.e. ~ 5.4 days after the INTEGRAL
trigger. We have taken multiple frames having an exposure time of 180
s in the R filter. We did not detect any optical afterglow candidate
in our single or stacked image within the INTEGRAL uncertainty circle
(Mereghetti et al., GCN 29429). Our non-detection is consistent with
Hu et al., GCN 29439 and Kumar et al., GCN 29451.


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


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

======================================================
2021-02-13 22:43:42   ~5.4          R   180*10      > 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.