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GCN Circular 29173

GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
2020-12-24T17:09:51Z (4 years ago)
Rahul Gupta at ARIES, India <>
Rahul Gupta (ARIES), Dimple (ARIES), Amit Kumar (ARIES), Vineet Ojha
(ARIES), Ankur Ghosh (ARIES), Amar Aryan (ARIES),  Shashi B. Pandey
(ARIES), and Kuntal Misra (ARIES) report:

We observed the optical afterglow ( Lipunov et al., GCN 29157; Gropp
et al., GCN 29158; Zhu et al., GCN 29159; Hu et al., GCN 29160;
Hosokawa et al., GCN 29164; Romanov et al., GCN 29165; Xin et al., GCN
29166; Belkin et al., GCN 29167; and Kumar et al., GCN 29168) of Swift
and Fermi detected GRB 201223A (Gropp et al., GCN 29158; and Wood et
al., GCN 29161) using the 1.3m Devasthal Fast Optical Telescope (DFOT)
and 1.04m Sampurnanand Telescope (ST) of Aryabhatta Research Institute
of Observational Sciences (ARIES), India. The observations were
started on 2020-12-23 at 19:01:46 UT. Multiple frames having an
exposure time of 300 s were taken in the I filter using DFOT and in
BVRI filters using ST. We clearly detected the optical counterpart at
the position reported by Gropp et al., GCN 29158.

The preliminary photometric estimate of the afterglow using I band
data of DFOT is the following :

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

2020-12-23   19:07:55      1.158              I              300*1
          18.71           0.04

------------------------------ ------------------------------
------------------------------ ------------------------------

The magnitude is not corrected for the Galactic and Host extinction in
the direction of the burst. Photometric calibration is performed using
the standard stars from the USNO-B1.0 catalogue.  Further processing
of data is going on.

This circular may be cited.
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