GCN Circular 37125
Subject
GRB 240809A: GIT afterglow observations
Event
Date
2024-08-10T04:21:01Z (2 years ago)
From
Varun Bhalerao at IIT Bombay <varunb@iitb.ac.in>
Via
Web form
T. Mohan, A. Mehla, R. Kumar, V. Swain, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of GRB 240809A detected by Swift (Evans et al., GCN 37110; optical follow-up Dubay et al GCN 37114; Jiang et al GCN 37116; Lipunov et al GCN 37117; Gottumukkala et al GCN 37122) with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2024-08-09 17:15:14 UT, i.e., 8.75 hours after the Swift trigger. We obtained one exposure of 300 seconds in the r' filter. In our image, we clearly detected the afterglow at the coordinates reported by Swift/UVOT Detection (Evans et al., GCN 37110). The photometry results follow as:
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| JD (mid) | t-t0 (hours) | Filter | Total Exposure (s) | Magnitude (AB) | Limiting mag |
| ----------------- | ------------ |------- | ------------------ | -------------- | ------------ |
| 2460532.218912037 | 8.75 | r' | 300 | 19.8 +/- 0.2 | 20.26 |
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Our observations are consistent with those reported by Dubay et al. in GCN 37114 and Jiang et al. in GCN 37116. The magnitude is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) 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 the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.