2014A&A...561A..55R

Information of small-diameter sources is extracted from the Sino-German λ6 cm polarisation survey of the Galactic plane carried out with the Urumqi 25-m telescope. We performed two-dimensional elliptical Gaussian fits to the λ6 cm maps to obtain a list of sources with total-intensity and polarised flux densities. The source list contains 3832 sources with a fitted diameter smaller than 16' and a peak flux density exceeding 30 mJy, so about 5xthe rms noise, of the total-intensity data. The cumulative source count indicates completeness for flux densities exceeding about 60 mJy. We identify 125 linearly polarised sources at λ6 cm with a peak polarisation flux density greater than 10 mJy, so about 3xthe rms noise of the polarised-intensity data. Despite lacking compact steep spectrum sources, the λ6 cm catalogue lists about 20% more sources than the Effelsberg λ21 cm source catalogue at the same angular resolution and for the same area. Most of the faint λ6 cm sources must have a flat spectrum and are either HII regions or extragalactic. When compared with the Green Bank λ6 cm (GB6) catalogue, we obtain higher flux densities for a number of extended sources with complex structures. Polarised λ6 cm sources density are uniformly distributed in Galactic latitude. Their number density decreases towards the inner Galaxy. More than 80% of the polarised sources are most likely extragalactic. With a few exceptions, the sources have a higher percentage polarisation at λ6 cm than at λ21 cm. Depolarisation seems to occur mostly within the sources with a minor contribution from the Galactic foreground emission.