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A VLBI and MERLIN Survey of faint,compact radio sources
Institution:1. Faculty of Built Environment, University of New South Wales Sydney, Australia;2. Faculty of Construction and Environment, Hong Kong Polytechnic University, Hong Kong;3. School of Civil and Environmental Engineering, University of New South Wales Sydney, Australia;1. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 China;2. University of Chinese Academy of Sciences, Beijing 100049, China
Abstract:We present preliminary results from a VLBI survey at λ=6 cm of a sample of 35 sources with flux densities of 2–100 mJy. These sources were selected from the VLA FIRST survey at λ=20 cm, in a 3 degree field around the bright calibrator 1156+295, simply by imposing S20>10 mJy and θ<5 arcsec. MERLIN observations at λ6 cm detected 70/127 of these sources with a threshold of 2 mJy at 50 mas resolution and the closest 35 of these to the calibrator were observed with the VLBA+EVN in snapshot mode at λ6 cm. These sources are a mixture of flat and steep-spectrum sources and include: weak flat-spectrum nuclei of large radio galaxies, low power AGN in nearby galaxies and radio quiet quasars. With these short observations, the sensitivity is limited and most appear as either core-jets or simple point sources on the milliarcsec scale. Nonetheless, it is encouraging that with only 10 minutes observation per source, at least 35% of all sources with S20>10 mJy can be detected and imaged with global 6 cm VLBI.
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