Near-Infrared Observations of the Z approximately 2.3 IRAS Source FSC 10214+4724

Near-infrared imaging and spectroscopy of the extremely luminous IRAS source FSC 10214+4724 have been obtained using the Cassegrain infrared camera on the 200 inch (5.08 m) Hale Telescope. A low-resolution spectrum (λ/dλ~100) in the 2.0-2.4 micron atmospheric window shows a very strong Hα line at the optically determined redshift z = 2.286. The observed rest-frame equivalent width of Hα is 0.07 + 0.02 micron, consistent with the largest values found in quasars. The images show an unresolved source, while the near-infrared colors are somewhat redder than the mean colors of quasars observed at the same redshift. The reddening inferred is A_v_~1.5 mag, with an upper limit of ~3.0 mag. The observations presented here cannot distinguish between starburst and quasar models for this source. Starburst models require ~10^12^ M_sun_ of stars to have been formed over 10^7^-10^8^ yr. If FSC 10214+4724 is a quasar, the reddening-corrected bolometric luminosity is approximately equal to the observed infrared luminosity.