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We present ultraviolet spectropolarimetry of the highly polarized Seyfert~1 nucleus of Mrk~486 and the low-polarization Seyfert~1/QSO I~Zw~1. These data were obtained using the {\sl Faint Object Spectrograph\/} aboard the {\sl Hubble Space Telescope\/} and span $\lambda\lambda$1600--3300. The high degree of linear polarization ($P \approx 2$--4\%) observed for Mrk~486 at optical wavelengths continues into the UV where $P\/$ reaches $\sim$7--8\% at 2000~\AA . We detect no difference between the polarization of prominent ultraviolet emission lines and the UV continuum. This is in contrast to previous optical investigations that have shown significant deviations from the local continuum polarization position angle at H$\alpha$ and H$\beta$. The UV polarization of I~Zw~1 is enigmatic given that optical observations have revealed a strong increase in polarization toward the blue in this object. However, no significant polarization was detected for this object in the {\sl HST\/} data. The UV results will be used to test and constrain scattering models proposed to explain the origin of the polarized flux in these AGNs.
This work is supported by NASA grant NAG~5-1630.
