GCN Circular 28876

K. Sharma (IITB), H. Kumar (IITB), P. Dorjay (IAO), J. Stanzin (IAO), U.
Stanzin (IAO), V. Bhalerao (IITB), G. C. Anupama (IIA), S. Barway (IIA),
report on behalf of the GROWTH-India collaboration:

We followed-up the optical afterglow ZTF20acozryr (Michael Coughlin et.
al., GCN #28841) of GRB 201103B, detected by the AGILE (GCN #28831) and IPN
(D. Svinkin et. al. GCN #28844), with 0.7 m GROWTH-India telescope. We
obtained 300-sec exposures in the SDSS r' filter over multiple nights.

Here are the photometric results from GIT observations:-

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JD (mid) | Filter | Exposure | mag | e_mag |

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2459160.322200 | r' | 300 x 20 | 21.08 | 0.08 |

2459163.145455 | r' | 300 x 30 | 21.91 | 0.06 |

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Combining our photometric results with r/r' band measurements of Michael
Coughlin et. al., GCN #28841; D. Xu et. al., GCN #28846; D. Xu et. al., GCN
#28847; S. Belkin et. al., GCN #28862; we conclude that the source is
fading with a power-law index of 1.16 +/- 0.07. The magnitudes are
calibrated against PanSTARRs PS1 data release, (Flewelling et al., 2018)
and are 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 (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).