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GCN Circular 34420

Subject
GRB 230812B: GIT optical follow-up
Date
2023-08-14T18:22:14Z (9 months ago)
From
Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>
Via
Web form
R. Kumar (IITB), A. Salgundi (IITB), V. Swain (IITB), H. Kumar (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:

We observed the field of the GRB230812B (Fermi GBM Team, GCN 34386) with 0.7m GROWTH-India Telescope (GIT). We started the observation from 14:46:44 UT on 2023-08-13, roughly 20 hours after the Fermi trigger. We obtained multiple frames of 300 sec each in the g' and r' bands. We detected the afterglow in our stacked images at the enhanced Swift XRT localization (Beardmore et al. GCN 34400). The details of the photometry are given in the below table:

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JD (mid) | t-t0 (days)| Filter | Exposure (s) | Magnitude (AB) |

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2460170.139773 | 0.85 | g' | 5 x 300 | 20.34 +/- 0.06 |
2460170.121745 | 0.83 | r' | 4 x 300 | 19.98 +/- 0.05 | 


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Our photometry values are consistent with the results submitted by other optical telescopes (Zheng & Filippenko, GCN 34395, Lipunov et al., GCN 34396, Salgundi et al., GCN 34397, Ackley et al., GCN 34398, Kuin et al. GCN 34399, Mao et al., GCN 34404, Odeh et al., GCN 34405, Moskvitin et al., GCN 34406, Leonini et al., GCN 34408, de Ugarte Postigo et al. GCN 34409 & 34410, Belkin et al., GCN 34412, and N. Ruocco et al., GCN 34413, N. Ruocco et al., GCN 34413, M. Shrestha et al., GCN 34416, C. Adami et al., GCN 34418, L. Moretti et al., GCN 34419).
We confirm that the candidate is decaying fast.

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/.
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