TITLE: GCN CIRCULAR NUMBER: 29657 SUBJECT: GRB 210306A: GIT optical follow-up DATE: 21/03/15 11:34:37 GMT FROM: Harsh Kumar at Indian Inst of Tech,Bombay H. Kumar(IITB), K. Sharma (IITB), J. Stanzin (IAO), A. Dutta(IIA), V. Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team: We observed GRB 210306A detected by Swift Burst Alert Telescope (V. D'Elia et. al., GCN 29597) and optical afterglow confirmed by (Alan M. Watson et. al., GCN 29598), with the 0.7m GROWTH-India Telescope (GIT). We obtained multiple exposures in the r' filter. We clearly detected the afterglow in our stacked image at R.A. = 08:39:49.99, DEC. = +60:12:19.09. The photometric results follow as: -------------------------------------------------------- JD (mid) | T_mid-T0(hrs) | Filter | Magnitude (AB) | -------------------------------------------------------- 2459280.20139 | 12.9 | r' | 20.87 +/0.05 | -------------------------------------------------------- The magnitude is in agreement with that reported by Z.P. Zhu et al., (GCN 29607), around the same time of our observation. The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018) 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 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).