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We report Swift observations of a sample of 92 bright soft X-ray selectedactive galactic nuclei (AGN). This sample represents the largest number of AGNobserved to study the spectral energy distribution (SED) of AGN withsimultaneous optical/UV and X-ray data. The principal motivation of this studyis to understand the SEDs of AGN in the optical/UV to X-ray regime and toprovide bolometric corrections which are important in determining the Eddingtonratio L/Ledd. In particular, we rigorously explore the dependence of the UV-EUVcontribution to the bolometric correction on the assumed EUV spectral shape. Wefind strong correlations of the spectral slopes alpha-x and alpha-UV withL/Ledd. Although Narrow-Line Seyfert 1 galaxies (NLS1s) have steeper alpha-xand higher L/Ledd than Broad-Line Seyfert 1 galaxies (BLS1s), their optical/UVto X-ray spectral slopes alpha-ox and optical/UV slopes alpha-UV are verysimilar. The mean SED of NLS1s shows that in general this type of AGN appearsto be fainter in the UV and at hard X-ray energies than BLS1s. We find a strongcorrelation between alpha-x and alpha-UV for AGN with X-ray spectral slopesalpha-x<1.6. For AGN with steeper X-ray spectra, both this relation and therelation between alpha-x and L/Ledd break down. At alpha-x$\approx$1.6, L/Leddreaches unity. We note an offset in the alpha-UV - L/Ledd relation betweenNLS1s and BLS1s. We argue that alpha-UV is a good estimator of L/Ledd andsuggest that alpha-UV can be used to estimate L/Ledd in high-redshift QSOs.Although NLS1s appear to be highly variable in X-rays they only vary marginallyin the UV.

The Simultaneous Optical-to-X-ray Spectral Energy Distribution of Soft X-ray Selected AGN observed by Swift