2017ApJ...848....8R

Modern transient surveys have begun discovering and following supernovae (SNe) shortly after first light-providing systematic measurements of the rise of Type II SNe. We explore how analytic models of early shock-cooling emission from core-collapse SNe can constrain the progenitor's radius, explosion velocity, and local host extinction. We simulate synthetic photometry in several realistic observing scenarios; assuming the models describe the typical explosions well, we find that ultraviolet observations can constrain the progenitor's radius to a statistical uncertainty of ±10%-15%, with a systematic uncertainty of ±20%. With these observations the local host extinction (A_V) can be constrained to a factor of two and the shock velocity to ±5% with a systematic uncertainty of ±10%. We also reanalyze the SN light curves presented by Garnavich et al. (2016) and find that KSN 2011a can be fit by a blue supergiant model with a progenitor radius of R_s 7.7+8.8(stat)+1.9(sys) R_☉, while KSN 2011d can be fit with a red supergiant model with a progenitor radius of R_s=111_{–21(stat)–1(sys)}^{+89(stat)+49(sys)} R_☉. Our results do not agree with those of Garnavich et al. Moreover, we re-evaluate their claims and find that there is no statistically significant evidence for a shock-breakout flare in the light curve of KSN 2011d.