s$^{-1}$]{}). Integration times are determined for a minimum S/N = 4 at $g=20.2$ mag. The spectroscopic pipeline performs basic image calibrations, as well as spectral extraction, sky subtraction, removal of atmospheric absorption bands, and wavelength and spectrophotometric calibration (Stoughton [et al.]{}2002). Finally, spectral classification is performed using cross-calibration with stellar, emission-line, and active galaxy templates. The Third Data Release (DR3; Abazajian [et al.]{} 2005) of SDSS contains 45,260 spectroscopically identified AGNs with $z < 2.3$. Of these, $\sim 3000$ have $z \leq 0.35$, and hence [H$\alpha$]{} in the bandpass.

From this sample we select objects with a high S/N ($\geq 25$ per pixel) and low galaxy contamination, so that we can unambiguously measure [$L_{5100}$]{}. We use the equivalent width (EW) of the Ca [ii]{} K $\lambda 3934$ line to estimate the degree of galaxy contamination; within the SDSS bandpass this is the highest-EW stellar absorption feature that is not confused with line emission. By artificially diluting composite galaxy spectra[^1] from Bernardi [et al.]{} (2003) with varying levels of featureless AGN continuum (which for a narrow spectral region is well approximated by a constant), we find that an EW cutoff of 1.5 Å for the Ca [ii]{} K line corresponds to 