We present 90cm Very Large Array imaging of the COSMOS field, comprising a circular area of 3.14 square degrees at 8.0"x6.0" angular resolution with an average rms of 0.5mJy/beam. The extracted catalogue contains 182 sources (down to 5.5{sigma}), 30 of which are multicomponent sources. Using Monte Carlo artificial source simulations, we derive the completeness of the catalogue, and we show that our 90cm source counts agree very well with those from previous studies. Using X-ray, NUV-NIR and radio COSMOS data to investigate the population mix of our 90cm radio sample, we find that our sample is dominated by active galactic nuclei. The average 90-20cm spectral index (S_{nu}{prop.to}{nu}^{alpha}^, where S{nu}_ is the flux density at frequency {nu} and {alpha} the spectral index) of our 90cm selected sources is -0.70, with an interquartile range from -0.90 to -0.53. Only a few ultra-steep-spectrum sources are present in our sample, consistent with results in the literature for similar fields. Our data do not show clear steepening of the spectral index with redshift. Nevertheless, our sample suggests that sources with spectral indices steeper than -1 all lie at z>~1, in agreement with the idea that ultra-steep-spectrum radio sources may trace intermediate-redshift galaxies (z>~1).

Cone search capability for table J/MNRAS/443/2590/catalog (90cm COSMOS source catalog)