GCN Circular 31997
Subject
GRB 220430A: GIT optical upper limits
Event
Date
2022-05-05T00:54:08Z (4 years ago)
From
Varun Bhalerao at Indian Inst of Tech <varunb@iitb.ac.in>
V. Swain (IITB), H. Kumar (IITB), K. Angail (IAO), V. Bhalerao (IITB), G. C. Anupama (IIA), S. Barway (IIA) report on behalf of the GIT team:
We observed GRB 220430A detected by Swift (Ambrosi et al. GCN #31972) and AGILE (Ursi et al. GCN #31975), with a 0.7m GROWTH-India Telescope (GIT). The observation started on 2022-04-30 at 14:23:56 UT, 30.65 min after the SWIFT BAT trigger. We obtained multiple 100-sec exposures in the r' and i' filters. The images were shallower than usual due to poor observing conditions. We did not detect any new source in our stacked image within the 2.0" circle around R.A.= 06h 30m 26.92s, Dec.= +09d 32' 51.1" (J.P. Osborne et al. GCN #31973). The obtained upper limits follow as:
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JD (mid) | T_mid-T0(hrs) | Exposure (sec) | Filter | Lim_mag (5-sigma) |
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2459700.10382 | 0.60 | 300 (stacked) | r' | > 19.26 |
2459700.10763 | 0.69 | 300 (stacked) | i' | > 18.68 |
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The upper limits are consistent with the Ambrosi et al., (GCN #31972), Groot et al. (GCN #31974), Pankov et al.(GCNC #31976), Dornic et al. (GCN #31977), V. Lipunov et al.(GCN #31978) and Y.-D. Hu et al. (GCN #31980). The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) 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 (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.