The UKIRT Infrared Deep Sky Survey and the search for the most distant   quasars
  The UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) has the necessary combination of filters (Y, J, H and K), depth (Y <~ 20.2) and area coverage (~4000 deg^2) to detect several redshift z >~ 6.4 quasars. The Third Data Release (DR3) included ~1000 deg^2 of LAS observations which have so far yielded two previously known z ~= 6 quasars and two new discoveries: ULAS J0203+0012, at z = 5.72; and ULAS J1319+0950, at z = 6.13. 
Daniel J. Mortlock (1), Mitesh Patel (1), Stephen J. Warren (1), Bram   P. Venemans (2), Richard G. McMahon (2), Paul Hewett...