In this paper we have presented the results of 21 extragalactic radio sources of VLBI observation at 5 GHz. The VLBI images of eleven sources and the correlated flux density information of the remaining 10 sources are given. The superluminal nature of four sources (DA193, 0420-014, 1334-127 and 2345-16) is confirmed and their physical parameters (, and ) are derived. Lorentz factors in the range are found, in agreement with their blazar nature. Two new superluminal candidates 1504-166 and 2243-123 are found, and finally three sources (1532+016, 2320-035, 2351-154) are imaged for the first epoch at VLBI resolution.Acknowledgements
The authors are grateful to the staff of Medicina, Noto, Hartebeesthoek, Urumqi, and Shanghai radio telescopes for support during the VLBI observations, and the correlator and computer groups at Medicina for support of our project. XYH thanks IRA-CNR and JIVE/NFRA for their hospitality during his visit to Italy and the Netherlands. XYH is very grateful to Dr. L.I. Gurvits for his valuable comments. XYH is supported by the National Science Foundation of China, PAN DENG Plan, and Su- Shu Huang Astrophysics Research Foundation of Academia Sinica. The research has made use of the NASA/IPAC extragalactic database (NED) which is operated by the Jet Propulsion laboratory, Caltech, under contract with the National Aeronautics and Space Adminstration.
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