1000 Days of the Lowest-frequency Emission from the Low-luminosity GRB 171205A

We report the lowest frequency measurements of gamma-ray burst (GRB) 171205A with upgraded Giant Metrewave Radio Telescope (uGMRT) covering a range from 250--1450 MHz and period $4-937$ days. It is first GRB afterglow detected at 250--500 second brightest uGMRT. Even though observed for nearly 1000 days, there no evidence transition to non-relativistic regime. also analyse archival ${\it Chandra}$ X-ray data on day $\sim 70$ 200$. find jet break analysis combined data. fit synchrotron emission arising relativistic, isotropic, self-similar deceleration as well shock-breakout wide-angle cocoon. Our allow us discern nature density circumburst medium. that profile deviates standard constant medium suggests exploded in stratified wind like shows absorbed part light curves are critical unravel environment. other published indicate radio has contribution two components: weak, possibly slightly off-axis surrounding wider cocoon, consistent results Izzo et al. (2019). The cocoon likely dominates early epochs, whereas starts dominate later resulting flatter lightcurves.