Detailed ultraviolet observations of the quasar 3C 273 with IUE

Abstract

We have obtained nine spectra of the quasar 3C 273 with the International Ultraviolet Explorer with the aim of combining them and obtaining a high signal-to-noise spectrum between 1100 and 3300 Å. This permits us to make a detailed analysis of the emission line intensity ratios and of the continuous energy distribution. We find evidence for a thermal contribution to the ultraviolet continuum. The ultraviolet spectrum of 3C 273, which we obtained, shows eight absorption lines at zero redshift due to the intervening material in our Galaxy. The C IVλ1550 absorption is much stronger in the spectrum of 3C 273 than in the spectra of halo stars. This is taken as evidence for the existence of a hot gaseous component in the outer regions of the halo of the Galaxy.