Publication Title

Future Directions in High Resolution Astronomy: The 10th Anniversary of the VLBA


ASP Conference Proceedings, Vol. 340

Publication Date


Document Type

Conference Paper

First and Last Page



The VSOP mission is a Japanese-led project to image radio sources with sub-milliarcsec resolution using an orbiting 8 m telescope, HALCA, along with global arrays of Earth-based telescopes. The orbit of HALCA generates VLBI baselines that are typically two to three times longer than can be obtained with solely ground-based VLBI (Hirabayashi et al. 1998). Approximately 25% of the observing time was devoted to a survey of the brightest, compact AGN at 5 GHz--the VSOP AGN Survey. From the Survey data we have generated high resolution images, and fit simple models to the primary radio components. From the model-fit parameters the core brightness temperature of the individual sources has been calculated. A significant fraction of the sources have core brightness temperatures in excess of 1012 K in the source frame.