Ultra-steep spectrum radio sources in SDSS

The sample of radio sources is selected from the catalogue of Kimball & Ivezic (2008AJ....136..684K) with flux densities at 325, 1400 and 4850MHz, using Westerbork Northern Sky Survey, NRAO VLA Sky Survey and Green Bank 6cm radio surveys and from flux measurements at 74MHz taken from Very Large Array Low-Frequency Sky Survey (Cohen et al. 2006, Cat.

VIII/79). We study radio galaxy spectral properties using radio colour-colour diagrams and find that our sample follows a single power law from 74 to 4850MHz.