NEAR-INFRARED SPECTROPHOTOMETRY OF 8 3CR RADIOGALAXIES - THE 1ST DETECTIONS OF [OIII]500.7 AND [SIII]953.2 EMISSION-LINES IN GALAXIES WITH Z-GREATER-THAN-1

We present the results of near-IR spectrophotometry of eight 3CR radiogalaxies with redshifts in the range 0.256 less-than-or-equal-to z less-than-or-equal-to 1.575. The narrow [O(III)]500.7 emission line was detected in 3C13 (z = 1.351), and the narrow [S(III)]953.2 emission line in 3C79 (z = 0.256), in the northern near-IR knot of 3C356 (z = 1.079) and marginally in 3C368 (z = 1.132). These emission lines are among the faintest to be detected with near-IR spectroscopy, and include the first measurements of [O(III)]500.7 and [S III]953.2 in any galaxy with z > l. We show that narrow-line emission can sometimes account for a substantial fraction (approximately 25 per cent) of the broad-band near-IR flux arising from the substructures of high-z radiogalaxies, but that this fraction is strongly dependent on, and therefore a valuable probe of, physical conditions within the substructures.