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We present an analysis of the intrinsic UV absorption in the Seyfert 1 galaxyMrk 279 based on simultaneous long observations with the Hubble Space Telescope(41 ks) and the Far Ultraviolet Spectroscopic Explorer (91 ks). To extract theline-of-sight covering factors and ionic column densities, we separately fittwo groups of absorption lines: the Lyman series and the CNO lithium-likedoublets. For the CNO doublets we assume that all three ions share the samecovering factors. The fitting method applied here overcomes some limitations ofthe traditional method using individual doublet pairs; it allows for thetreatment of more complex, physically realistic scenarios for theabsorption-emission geometry and eliminates systematic errors that we show areintroduced by spectral noise. We derive velocity-dependent solutions based ontwo models of geometrical covering -- a single covering factor for allbackground emission sources, and separate covering factors for the continuumand emission lines. Although both models give good statistical fits to theobserved absorption, we favor the model with two covering factors because: (a)the best-fit covering factors for both emission sources are similar for theindependent Lyman series and CNO doublet fits; (b) the fits are consistent withfull coverage of the continuum source and partial coverage of the emissionlines by the absorbers, as expected from the relative sizes of the nuclearemission components; and (c) it provides a natural explanation for variabilityin the Ly$\alpha$ absorption detected in an earlier epoch. We also explorephysical and geometrical constraints on the outflow from these results.Comment: 17 pages, 15 figures (9 color), emulateapj, accepted for publication  in The Astrophysical Journa

X‐Ray/Ultraviolet Observing Campaign of the Markarian 279 Active Galactic Nucleus Outflow: A Global‐Fitting Analysis of the Ultraviolet Absorption