Program: GN-2009B-Q-49

*Targets may change at Phase-II since we update the target selection as new survey data become available. * High-redshift QSOs are highly important objects in various scientific aspects. For example, their spectra reveal the onset of reionization of the intergalactic medium (Gunn-Peterson trough). We need to search QSOs at z>7 to extend the reionization probe to the earlier Universe. We have carefully selected z~7 QSO candidates from the UKIDSS. We propose optical specroscopy of most promising candidates. Finding no QSOs does not mean a waste of telescope time, but provides us with precious information on the evolution of the QSO luminosity function between z=6 and z=7. A discovery of the first z>7 QSO would leave a huge impact to the astronomical community.