supernovae: individual: PTF12gzk

We present the discovery and extensive early-time observations of the Type Ic supernova (SN) PTF12gzk. Our light curves show a rise of 0.8 mag within 2.5 hr. Power-law fits (f(t)vprop(t - t ${}_0$)${}^n$) to these data constrain the explosion date to …