for the site. For HET, BTA and NTT, the resolution near 6000Å is about 10Å, 14Å, and 12Å respectively.

Light Curve Evolution {#res:broadband}
=====================

According to theoretical interpretation, the entire broadband evolution of Type II SNe can be segmented into three phases: the rising phase, the plateau phase and the nebular phase.

![image](ROTSE_obs.ps){width="13cm"}

The Rising Phase {#res:rise}
----------------

The rising phase of the light curve is associated with the shock breakout phenomenon having been theoretically predicted for an SN explosion, in which, the radiation-dominated shock wave, generated through the reversal of iron core-collapse, starts to propagate outward through the onion shell-like layers of the progenitor; when the shock reaches regions with an optical depth of a few tens to unity, the radiation behind the shock escapes the outer surface giving rise to a hot (T $>10^5$ K) fireball which emits quasi-black body radiation in UV and soft-Xrays. This phenomenon is called shock breakout and depending on envelope mass, density structure and wind properties of the progenitor, the breakout light curve may last from a few hours to few a days (@grassberg71 [@chevalier76; @falkarnett77]). Due to the short timescale, the detection of shock breakout is rare, and only recently were, the 