2000ApJ...533L..75S

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 R_AB>26.3 (3 σ limit in a 3" diameter region), I_AB=23.8, and z_AB=23.4. The Keck/Low-Resolution Imaging Spectrometer spectrum shows broad Lyα/N V λ1240 emission and sharp absorption decrements from the highly redshifted hydrogen forests. The fractional continuum depression due to the Lyα forest is D_A=0.90. RD J030117+002025 is the least luminous high-redshift quasar known (M_B~-22.7).