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GCN Circular 30402

GRB 210706A: GIT optical upper limits
2021-07-07T12:39:54Z (3 years ago)
Harsh Kumar at Indian Inst of Tech,Bombay <>
H. Kumar (IITB), R. Norbu (IAO), V. Bhalerao (IITB), G. C. Anupama (IIA),
S. Barway (IIA) report on behalf of the GIT team:

We observed GRB 210706A detected by Swift/BAT-GUANO (see A. Tohuvavohu et
al. GCN #30393) with 0.7m GROWTH-India Telescope (GIT). We obtained
multiple 100-second images in g', r' and i' bands, interspersed with each
other. The total exposure in each band was 1000 seconds. We did not detect
any new source in our stacked images within the 3.2 arcsec circle, around
the swift XRT position centered at RA: 20h 47m 58.73s Dec: +13d 19' 01.0"
(GCN #30399). Also, we did not detect any new transient within the full 5
arcmin circle around the Swift/BAT-GUANO position (GCN #30393). The
obtained upper limit follow as:


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


  2459402.343657 | 11.95 |  g' | > 20.86 |

  2459402.346588 | 12.02 |  r' | > 21.00 |

  2459402.349518 | 12.09 |  i' | > 20.32 |


The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018)
and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India ( It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).
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