The [Oiii] Emission‐Line Nebula of thez= 3.594 Radio Galaxy 4C +19.71

We have imaged the z=3.594 radio galaxy 4C +19.71 in the light of theredshifted [OIII] 5007 angstrom emission line, using a narrow-band filtercentered at 2.3 microns with the Near Infrared Camera on the Keck Telescope.The [OIII] nebula of 4C +19.71 has a size of 74 x 9 kpc, and a luminosity of 3x 10^37 W. The rest frame equivalent width of the 5007 line, averaged over theentire nebula, is 560 angstroms. The length of the major axis of the [OIII]emission is nearly identical to the separation of the radio lobes seen at 1465MHz (Rottgering, et al. 1994), and the position angle of the nebula is the sameas that of the two radio lobes. In addition, 4C +19.71 follows the opticalemission line vs. radio power correlation seen in other powerful radiogalaxies. The [OIII] and Lyman alpha emission line luminosities suggest thatthe ionized gas mass lies in the range of 2 x 10^8 - 10^9 solar masses. The O/Hratio in the nebula is at least a few tenths solar, and may be as high as afactor of three above solar, indicating a previous phase of star formation in4C +19.71. Thirty five percent of the total K-band flux is contributed by the5007 angstrom emission line, and the continuum of 4C +19.71 has a K=19.6 mag.This places 4C +19.71 along the K-z relation found for other radio galaxies andradio loud quasars. If the continuum is dominated by starlight, the host galaxyhas a rest frame visual luminosity of about 40L*. There are no candidateemission-line objects at the redshift of 4C +19.71 having [OIII] rest frameequivalent widths of more than about 2% that of the radio galaxy itself withina volume of 212 cubic Mpc.Comment: plain LaTex with 3 postscript figures. ApJ accepte