  It is difficult to identify the distant galaxies selected in existing
submillimeter (submm)-wave surveys, because their positional accuracy is only
several arcseconds. Currently, centimeter-wave VLA observations are required in
order to determine sub-arcsec positions, and so to make reliable optical
identifications. Carilli & Yun (1999) pointed out that the ratio of the radio
and submm-wave flux densities provides a redshift indicator for dusty
star-forming galaxies, when compared with the tight correlation observed
between the far-infrared and radio flux densities for low-redshift galaxies.
This method provides a useful, albeit imprecise, indication of the distance to
a submm-selected galaxy. However, because the degeneracy between the effects of
increasing the redshift of a galaxy and decreasing its dust temperature is not
broken, it does not provide an unequivocal redshift estimate.
