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GCN Circular 33284

GRB 230204B: 3.6m DOT optical observation
2023-02-06T13:35:11Z (a year ago)
Amit Kumar Ror at ARIES <>
Amit K. Ror, Ankur Ghosh, Brajesh Kumar, Rahul Gupta, A. Aryan, Dimple, S.
B. Pandey, and K. Misra (ARIES) report:

We observed the field of GRB 230204B detected by MAXI/GSC (Serino et al.
2023, GCN 33265) using the 3.6m Devasthal Optical Telescope located at the
Devasthal observatory of the Aryabhatta Research Institute of Observational
Sciences (ARIES), Nainital, India.

We have taken multiple frames having an exposure time of 180 sec each in
the r filter. We stacked the images after the alignment. We clearly detect
the optical transient discovered by Swain and Kumar et al. 2023 (GCN 33269)
in the stacked images. The estimated preliminary magnitude is the following:

Date Start_UT T_start-T0 (days) Filter  Exp time (sec)       magnitude
2023-02-06 01:49:47.93   ~1.168          r        180 sec*10
 21.04 +/- 0.04

The detection of the optical transient is consistent with the observation
of Swain and Kumar et al. 2023 (GCN 33269), Smartt et al. 2023 (GCN 33278),
and Saccardi et al. 2023 (GCN 33281)

The limiting magnitude quoted is not corrected for the galactic and host
extinctions in the direction of the transient. Photometric calibration is
performed using the standard stars from the Pan-STARRS catalog.

This circular may be cited. The 3.6m Devasthal Optical Telescope (DOT) is a
recently commissioned facility in the Northern Himalayan region of India
(long: 79 41 04E, lat: 29 21 40N, alt: 2540m) owned and operated by the
Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital ( The authors of this GCN circular thankfully
acknowledge the consistent support from the staff members to run and
maintain the 3.6m DOT.
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