title: Discovery of a Color-selected Quasar at z = 5.50.
abstract: We present observations of RD J030117+002025, a quasar at z=5.50 discovered from deep, multicolor, ground-based observations covering 74 arcmin2. This is the most distant quasar or active galaxy currently known. The object was targeted as an R-band dropout, with RAB>26.3 (3 sigma limit in a 3&arcsec; diameter region), IAB=23.8, and zAB=23.4. The Keck/Low-Resolution Imaging Spectrometer spectrum shows broad Lyalpha/N v lambda1240 emission and sharp absorption decrements from the highly redshifted hydrogen forests. The fractional continuum depression due to the Lyalpha forest is DA=0.90. RD J030117+002025 is the least luminous high-redshift quasar known (MB approximately -22.7).
authors.initials: D
authors.lastname: Stern
authors.initials: H
authors.lastname: Spinrad
authors.initials: P
authors.lastname: Eisenhardt
authors.initials: AJ
authors.lastname: Bunker
authors.initials: S
authors.lastname: Dawson
authors.initials: SA
authors.lastname: Stanford
authors.initials: R
authors.lastname: Elston