■ [Recurrent Nova] U Sco : update
We performed the photometric and spectroscopic observations of the recurrent nova U Sco. The light curve show that this object evolved in the plateau phase. The radiations emitted in this stage are composed to the black body temperature from the optically thick wind and the free-free emissions from the irradiations of the accretion disk on the central white dwarf. The spectrum obtained on Feb. 5 shows that an weak emission line appears at 5400A and the emissions of the HeI 5876 and 7065 simultaneously begin to weaken. The weak emissions line at 5400A is thought to be HeII, which had already been identified in the spectra obtained 6 days after the 1987 outburst (Sekiguchi et al. 1988). Such an appearance of the higher excited level line indicate that the optically thick photosphere would recede enough. We will be able to the research the higher temperature regions in the inner shell comparing to that at the previous phase.