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GCN Circular 25560

GRB 190829A: GROWTH India detection of afterglow
2019-08-29T22:55:45Z (5 years ago)
Varun Bhalerao at Indian Inst of Tech <>
H. Kumar, V. Bhalerao (IITB), Jigmat Stanzin, G C Anupama, S. Barwe (IIAP) report on behalf of the GROWTH-India collaboration:

We observed the field of 190829A (Fermi GBM Team, GCN 2555; Dichiara et al., GCN 25552) with the GROWTH-India telescope. We obtained multiple 500 second exposures in g and r, starting 51 minutes after the event. We clearly detect an optical afterglow in all filters. Preliminary photometry values in g band are quoted below.

     JD           dt_minutes   ap_mag   Mag_err
2458725.366  51.16  16.93   0.01
2458725.372  59.80  17.21   0.02
2458725.394  91.48  18.00   0.12
2458725.400 100.12  18.08   0.04

The data are consistent with a power-law decline with a slope of 1.6. In addition, we also obtained an r band data point at JD 2458725.385, detecting the afterglow clearly with m_r = 16.475 +- 0.013, broadly consistent with Xu et al. (GCN 25555)

We caution that these photometry values are contaminated by flux from the host galaxy, and the afterglow brightness has been overestimated. 

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).

[Per author's request, the inclusion of discussion of a second GRB (GRB190701A) was an accident.
It has been removed from the archived copies.]
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