[vsnet-grb-info 26689] GRB 201020A: 1.3m DFOT, optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28789
SUBJECT: GRB 201020A: 1.3m DFOT, optical upper limits
DATE:    20/10/27 05:34:21 GMT
FROM:    Amit Kumar at ARIES, India  <amitkundu515 at gmail.com>

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

We observed the field of GRB 201020A (E. Ambrosi et al., GCN 28696)
with the 1.3m Devasthal Fast Optical Telescope (DFOT)
at Devasthal observatory of Aryabhatta Research Institute of
observational sciencES (ARIES), India.

Multiple frames of the GRB field were obtained in the Bessel R and
I-bands (15*120sec in each filter).
Preliminary photometry on stacked images were performed and calibrated
against nearby USNO-B1 stars.
We do not detect any OT candidate (see Adachi et al. GCN 28697;
Lipunov et al. GCN 28700; Fu et al. GCN 28701;
Belkin et al. 28703; Pankov et al. GCN 28708; Kumar et al. GCN 28711;
Paek et al. 28713; Kann et al. 28717; Gokuldass et al. 28737; Siegel
et al. 28742 and Kumar et al. GCN 28747) within the enhanced XRT
position (Osborne et al., GCN 28698).

The 3-sigma upper limits at the location of the afterglow are as follows:

DATE       Start UT   Filter  Exposure(sec)    Lim_mag (3-sigma)
2020-10-24 12:51:08    I        15*120            >22.1
2020-10-24 13:23:45    R        15*120            >22.5

The estimated magnitudes have not been corrected for the Galactic
extinction in the direction of the GRB. This massage may be cited.