| Abstract : | Gamma-Ray Bursts (GRBs) are among the most energetic events in the Universe. The afterglows of GRBs span the whole electromagnetic spectrum, including optical bands. These afterglows decay rapidly, following a typical power law index of -1.2. Such high evolution rates make it hard to observe these candidates for a longer duration. Therefore, a very rapid turnaround time is required to get valuable science. Here, we present the follow-up of GRB events in the last four years using the GROWTH-India Telescope (GIT) – India’s first fully robotic telescope. GIT, with its automated triggering capabilities, has detected more than 20 afterglows. We present the automated triggering development and its importance in afterglow follow-up, discoveries, and scientific results from a few interesting GRB afterglows. The afterglow of GRB 210204A is one such candidate for which we did extensive follow-up with Indian facilities led by GIT. We detected two optical flares in the afterglow at 7.6 × 10^5 s and 1.1 × 10^6 s after the burst – the most delayed flaring ever detected in a GRB afterglow. After investigating possible causes for this flaring, we conclude that the most likely cause is a refreshed shock in the jet. With the rapid and long-term systematic GIT study of these afterglow candidates, we highlight the possibility of more late-time flaring events being detected in the future. We emphasise the importance of rapid humanless follow-up as the key to catching unprecedented science of the GRB afterglows. |
