Galaxies at z>4.5

We present the results of ground-based and HST imaging studies targeted on z>4.5 quasar fields. High-redshift galaxies identified in deep narrow-band Lyman alpha images of the fields surrounding the quasars BR1202-0725 (z=4.694) and BR2237-0607 (z=4.558) have been confirmed with follow-up spectroscopy using the LRIS spectrograph on the Keck 10m telescope. These high-redshift galaxies are typically only moderately luminous objects and their sub-L* magnitudes imply star formation rates of only a few solar masses per year. For BR1202-0725 tip-tilt imaging in Lyman alpha at the UH 2.2m telescope and deep narrow-band IR imaging in [OII] at CFHT reveals a complex and structured system which may be merging to produce the host galaxy of the quasar. For BR2237-0607 the Lyman-alpha-emitting galaxies show the strong Lyman alpha emission and weak continuum expected for objects before substantial chemical enrichment and consequent dust formation and extinction has occurred. These objects appear to be galaxies in their first outburst of star formation.