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GCN Circular 33149

GRB 221231A: 3.6m DOT optical upper limit
2023-01-04T13:56:14Z (a year ago)
Amit Kumar Ror at ARIES <>
Amit K. Ror, Rahul Gupta, S. B. Pandey, A. Aryan, A. Ghosh, Dimple, and K.
Misra (ARIES) report:

We observed the field of GRB 221231A detected by Fermi/GBM (2022, GCN
33129) using the 3.6m Devasthal Optical Telescope of ARIES Nainital. We
have taken multiple frames having an exposure time of 200 sec in the r
filter. We stacked the images after the alignment. We did not find any
evidence of an afterglow candidate inside the Swift XRT error circle (Perri
et al. 2023, GCNs 33135 and 33139). We obtained the limiting mag of ~ 21.7
mag at ~ 1.87 days post-detection. The non-detection of the optical
afterglow is consistent with Odeh 2023, GCN 32876.

The limiting magnitudes quoted are not corrected for the Galactic and host
extinction in the direction of the burst. Photometric calibration is
performed using the standard stars from the Pan-STARRS catalog.

This circular may be cited. 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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