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We present initial results from the first systematic survey of luminous$z\sim 5.5$ quasars. Quasars at $z \sim$ 5.5, the post-reionization epoch, arecrucial tools to explore the evolution of intergalactic medium, quasarevolution and the early super-massive black hole growth. However, it has beenvery challenging to select quasars at redshifts 5.3 $\le z \le$ 5.7 usingconventional color selections, due to their similar optical colors to late-typestars, especially M dwarfs, resulting in a glaring redshift gap in quasarredshift distributions. We develop a new selection technique for $z \sim$ 5.5quasars based on optical, near-IR and mid-IR photometric data from SloanDigital Sky Survey (SDSS), UKIRT InfraRed Deep Sky Surveys - Large Area Survey(ULAS), VISTA Hemisphere Survey (VHS) and Wide field Infrared Survey Explorer(WISE). From our pilot observations in SDSS-ULAS/VHS area, we have discovered15 new quasars at 5.3 $\le z \le$ 5.7 and 6 new lower redshift quasars, withSDSS z band magnitude brighter than 20.5. Including other two $z \sim$ 5.5quasars already published in our previous work, we now construct an uniformquasar sample at 5.3 $\le z \le$ 5.7 with 17 quasars in a $\sim$ 4800 squaredegree survey area. For further application in a larger survey area, we applyour selection pipeline to do a test selection by using the new wide field Jband photometric data from a preliminary version of the UKIRT Hemisphere Survey(UHS). We successfully discover the first UHS selected $z \sim$ 5.5 quasar.

Discovery of 16 New z ~ 5.5 Quasars : Filling in the Redshift Gap of Quasar Color Selection