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GCN Circular 32886

Subject
GRB 221028A: HCT optical upper limit
Date
2022-10-29T08:49:36Z (a year ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar (IITB), A. Dutta (IIA), D.K. Sahu (IIA), G. C. Anupama (IIA), S.
Barway (IIA), V. Bhalerao (IITB), R. Gupta (ARIES), K. Misra (ARIES), D.
Panchal (ARIES), S.B. Pandey (ARIES), report on behalf of the HCT team:

We observed GRB 221028A detected by Swift-BAT (A. Y. Lien et al. GCN #
32874) with the 2.0m Himalayan Chandra Telescope (HCT) of the Indian
Astronomical Observatory (IAO). We obtained exposures in the Bessel V, Rc
and Ic filters and did not detect any afterglow within the Swift-XRT
uncertainty circle (A. Y. Lien et al. GCN # 32874). The obtained upper
limits follow as:

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

 JD (mid) | T_mid-T0(hrs) | Exposure (sec) | Filter | Lim_mag (5-sigma) |

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

 2459881.075085 | 0.52 | 60  | Rc | > 19.94 |

 2459881.091424 | 0.92 | 300 | Rc | > 22.06 |

 2459881.1037215| 1.21 | 300 | Ic | > 20.74 |

 2459881.108775 | 1.33 | 420 | V | > 22.30 |

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

The upper limits are consistent with Kumar et al., GCN #32876; Hu et al.,
GCN #32878; Lipunov et al., GCN #32879, R. Strausbaugh et al., GCN #32881.
The reported magnitudes are in the AB system of magnitude, calibrated
against PanSTARRS DR1 (Chambers et al., 2016) using Lupton's transformation
equations available at
http://classic.sdss.org/dr4/algorithms/sdssUBVRITransform.html#Lupton2005
and not corrected for Galactic extinction.

These observations were carried out under the ToO program HCT-2022-C3-P12.
We thank the HCT staff for their support during the observations. The
Indian Astronomical Observatory is operated by the Indian Institute of
Astrophysics, Bengaluru, India.
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