The First Caltech-Jodrell Bank VLBI Survey. I. λ = 18 Centimeter Observations of 87 Sources

Creators: Polatidis, A. G.; Wilkinson, P. N.; Xu, W.; Readhead, A. C. S.; Pearson, T. J.; Taylor, G. B.; Vermeulen, R. C.

Abstract

We present the first results from the first Caltech-Jodrell Bank VLBI survey (the CJ1 survey). The CJ1 sample includes 135 radio sources with total flux density 1.3 Jy > S_(6 cm) ≥ 0.7 Jy, declination δ_(1950) ≥ 35°, and Galactic latitude |b^II| > 10°. It extends the flux density limit of the complete "PR" sample studied by Pearson & Readhead from 1.3 to 0.7 Jy and increases the total number of sources from 65 to 200. The complete survey includes VLBI images at both λ- 18 and 6 cm of all the objects in the extended sample that have cores strong enough to be mapped with the Mark II VLBI system. These images provide a large enough sample to study, for example, the variety of morphologies exhibited by compact radio sources, cosmological evolution, superluminal motion, and misalignment between parsec-scale and kiloparsec-scale radio structures. In this paper we present λ-18 cm VLBI observations of 56 CJ1 and 3l PR sources made in 1990-1991, including images of 82 sources. The observations were made with a "snapshot" technique in which each source was observed in three 20-30-minute scans using an array of 12-16 antennas. The images have resolution 3-10 mas and dynamic range greater than 100:1. Later papers in the series will present the remaining λ-18 cm observations, the λ-6 cm observations, and the analysis and interpretation of the results.

Additional Information

© 1995 The American Astronomical Society. Received 1993 December 30; accepted 1994 November 2. We thank the staffs at the observations in the European and the U.S. VLBI Networks for their efforts during the CJ 1 survey. We also thank Dr. Leonid Matveyenko and the staffs of the telescopes in the former Soviet Union who made special efforts to participate in these observations. A.G. P. acknowledges the receipt of a British Council Fellowship for the year 1991. The work at the California Institute of Technology was supported by the National Science Foundation (grants AST-8814554 and AST-9117100). Some of the data in Table 1 were obtained by way of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, Caltech, under contract with the National Aeronautics and Space Administration. We are grateful to the referee, Margo Aller, for helpful comments.

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