Rotational modulation of the ultraviolet line fluxes from the RS CVn star IIPegasi

The exceptional in-orbit performance of the International Ultraviolet Explo rer (IUE) for more than eighteen years has made it possible to accumulate a n invaluable database of ultraviolet observations of a wide variety of obje cts and, in particular of active stars. Byrne et al. (1998) -hereafter Pape r I-have presented a multiwavelength campaign of observations of the RS CVn star II Peg, partially based on one of the latest series of IUE spectra of this system. Here we investigate issues raised in Paper I such as the rota tional modulation of chromospheric and transition region line fluxes and th e long-term trends in the ultraviolet emission during the operational perio d of the instrument, the definition of a mean quiescent state and the chang es operated in the radiative output by the ocurrence of the most energetic flare detected in this star. We also perform a differential emission measur e analysis based on the emission line fluxes and construct empirical models of the atmosphere of this star.