Top panel: Early-time r-band light curve of ASASSN-20jq. This also includes the first photometric detection of ASASSN-20jq made by PS in the z band, which has been S-corrected to the SDSS r-band system. Also plotted is the ATLAS o-band nondetection limit reported previously. Overplotted the r-band light curve is the best MCMC-fit of a single power-law function (solid curve) with inferred probability limits (shaded region). Bottom panel: 2D probability density of MCMC sample between the fit parameters – time of first light t_first and power-law index α. Having a confirmed detection at −19 days (vertical blue dashed line), only the region in green is valid parameter space. The contours correspond to 68% and 95% confidence intervals. The solid black lines indicate the mean of the MCMC sample for parameters t_first = −20.4 days (vertical) and α = 1.99 (horizontal).