The Pioneer Venus Orbiter ultraviolet spectrometer (PVOUVS) routinely obtained interplanetary hydrogen Lyman &agr; data while viewing ecliptic latitudes near 30 ¿S from 1978 to 1992 (during solar cycles 21 and 22). We describe hot models for this interplanetary Lyman &agr; data that include the solar cycle variation of (1) the solar flux, as a function of latitude and longitude; (2) the radiation pressure on hydrogen atoms; (3) the solar wind flux; (4) the solar EUV flux; and (5) the multiple scattering correction to an optically thin radiative transfer model. These models make use of solar radiation flux parameters (solar wind, solar EUV, and solar Lyman &agr;) from spacecraft and ground-based solar proxy observations. Comparison of the upwind data and model indicates that the ratio of the solar Lyman &agr; line center flux (responsible for the interplanetary signal) to the observed solar Lyman &agr; integrated flux is constant to within ~20%, with an effective line width near 1.1 ¿. Averaging the solar radiation pressure and hydrogen atom lifetime over 1 year before the observation reproduces the upwind intensity time variation but not the downwind. A better fit to the downwind time series is found using the 1 year average appropriate for the time that the atoms passed closest to the sun. Solar Lyman &agr; measurements from two satellites are used in our models. Upper Atmosphere Research Satellite (UARS) solar Lyman &agr; measurements are systematically higher than Solar Mesosphere Explorer (SME) values and have a larger solar maximum to solar minimum ratio. UARS-based models work better than SME-based models in fitting the PVOUVS downwind time series Lyman &agr; data. ¿ 1998 American Geophysical Union