Program: GN-2007A-Q-80

The Chandra Multiwavelength Project (ChaMP) is measuring the luminosity function of X-ray selected AGN out to $z$$\sim$5. to determine the history of supermassive black hole accretion. While we have evidence of a decline in the space density of AGN at $z$$>$3, we must increase our completeness at faint optical magnitudes ($21.5<i^{\prime}<23.5$), where the majority of high redshift and/or low-luminosity AGN lie. With our deep NOAO/MOSAIC ($g^{\prime}, r^{\prime}$, $i^{\prime}$) photometry, we identify several $z>4$ quasar candidates per {\em Chandra} field using optical color criteria, but with no stellar contamination ($\lesssim\,5\%$) thanks to \fxfopt. These 3 nights of Gemini time with GMOS-N are ALREADY AWARDED through the Chandra/NOAO Joint time process. We will acquire Gemini/GMOS spectra of 49 faint {\em Chandra} X-ray counterparts with $\ip$$<$23.5 in 3 prime fields (6 masks) accessible to Gemini/GMOS this semester. These faint redshifts will greatly increase our completeness in the faint corner of our \fxfopt\, selection plane, crucial to an accurate measurement of the luminosity function at high redshift. At the same time we will identify 7 of our best $z$$>$4 X-ray AGN candidates.