The CYDER Survey: First Results
  We present the Calan-Yale Deep Extragalactic Research (CYDER) Survey. The broad goals of the survey are the study of stellar populations, the star formation history of the universe and the formation and evolution of galaxies. The fields studied include Chandra deep pointings in order to characterize the X-ray faint populations. Here we present the results on the first fields studied. We find that the redshift distribution is consistent with that found in the Chandra Deep Field North. The distribution of hardness ratios is, however, softer in our sample. We find a high redshift quasar, CXOCY J125304.0-090737 at z=4.179, which suggests that the abundance of low luminosity high redshift quasars may be larger than what would be expected from reasonable extrapolations from the quasar optical luminosity function. 
F. J. Castander (1,2,3), E. Treister (2,3), J. Maza (2), P. Coppi (3),   T. Maccarone (4), S. Zepf (5), R. Guzman (6), M. T....