Program: GS-2008B-C-4

We are currently undertaking a spectroscopic survey of luminous AGN and quasars selected in the mid-infrared from {\em Spitzer} shallow surveys. Mid-infrared selection is much less biased with respect to obscuration than optical and X-ray techniques, and hence enables the discovery of obscured quasars as well as normal, unobscured ones. Our survey therefore provides an unique opportunity to construct luminosity functions for both obscured and unobscured quasars selected in the same way and covering similar redshifts and luminosities. Our 4m class spectroscopic observations have so far have yielded about 150 redshifts, but our luminosity functions are lacking lower luminosity objects at high redshift and high luminosity objects at low redshift. We will use GMOS at Gemini S to find lower luminosity $z > 1$ obscured quasars by targeting objects with faint 24$\mu$m fluxes, and use the Goodman Spectrograph at SOAR to target bright 24$\mu$m objects. Filling out these missing portions of the luminosity/redshift plane will allow us to disentangle any luminosity dependence of the obscured quasar fraction from its evolution with redshift. This will allow us to test models of the obscured quasar population, in particular at the highest redshifts and luminosities where we are seeing a previously undiscovered population of obscured objects.