A new search for distant radio galaxies in the Southern hemisphere --
  II. 2.2 micron imaging
  We have compiled a sample of 234 ultra-steep-spectrum (USS) selected radio
sources in order to find high-redshift radio galaxies. The sample covers the
declination range -40deg < DEC < -30deg in the overlap region between the
1400-MHz NRAO VLA Sky Survey, 408-MHz Revised Molonglo Reference Catalogue and
the 843-MHz Sydney University Molonglo Sky Survey (the MRCR-SUMSS sample). This
is the second in a series of papers on the MRCR-SUMSS sample, and here we
present the K-band (2.2 micron) imaging of 173 of the sources primarily from
the Magellan and the Anglo-Australian Telescopes. We detect a counterpart to
the radio source in 93% of the new K-band images which, along with previously
published data, makes this the largest published sample of K-band counterparts
to USS-selected radio galaxies. The location of the K-band identification has
been compared to the features of the radio emission for the double sources. We
find that the identification is most likely to lie near the midpoint of the
radio lobes rather than closer to the brighter lobe, making the centroid a less
likely place to find the optical counterpart. 79% of the identifications are
less than 1 arcsec from the radio lobe axis. These results differ from studies
of low-redshift radio samples where the environments are typically not nearly
so dense and disturbed as those at high redshift. In contrast to some
literature samples, we find that the majority of our sample shows no alignment
between the near-infrared and radio axes. Several different morphologies of
aligned structures are found and those that are aligned within 10 degrees are
consistent with jet-induced star formation. ...abridged...
