We constructed radio spectra for ~1400 UTR-2 sources and find that 46% of
them have concave curvature. Inspection of NVSS maps of 700 UTR sources
suggests that half of all UTR sources are either blends of two or more sources
or have an ultra-steep spectrum (USS). The fraction of compact USS sources in
UTR may be near 10%. Using NVSS and the Digitized Sky Survey(s) we expect to
double the UTR optical identification rate from currently ~19%.Comment: 2 pages, no figures; to appear in Proc. "Observational Cosmology with
the New Radio Surveys", eds. M. Bremer, N. Jackson & I. Perez-Fournon, Kluwer
Acad. Pres
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