The VSOP 5 GHz Continuum Survey:
The Pre-launch VLBA Observations

We have imaged with milliarcsecond resolution at 5 GHz 374 strong flat-spectrum radio sources north of declination -44° using the VLBA in June 1996. The source sample was compiled from the source list for the VLBI Space Observatory Programme (VSOP) Survey Program. About 250 of the sources observed with the VLBA had correlated flux densities at least 0.3 Jy on the longest VLBA baseline and these sources are currently being observed with VSOP at 5 GHz. Here we present the results from the VLBA pre-launch observations (VLBApls): the color and contour display of the images, the correlated flux density dependence with u-v distance, and improved positions for 62 sources. Cross-referencing with other major VLBI surveys are also given for many sources.

The observations were made with the VLBA for 22 hours on 5-6 June 1996. The total observing bandwidth was 64 MHz. The frequency coverage was not contiguous, but spanned the range 4.60 GHz to 5.09 GHz. This wide frequency range permitted the determination of accurate group delays from which precise source positions could be determined. Each source was observed once, for about 150 seconds.

The data were processed with the NRAO AIPS software package and the Caltech Difmap package. A typical clean image has an rms noise level of 2 mJy/beam and a nominal resolution of 3.5 mas x 1.5 mas.

If you make use of the data presented here, please refer to the following publication:
Fomalont E.B., Frey S., Paragi Z., Gurvits L.I., Scott W.K., Taylor A.R., Edwards P.G., Hirabayashi H. (2000), The VSOP 5 GHz Continuum Survey: The Pre-launch VLBA Observations, The Astrophysical Journal Supplement, Vol. 131, pp. 95-183 (November 2000)

This database can also be accessed from mirror sites in   Hungary ,  The Netherlands ,  Canada ,  and   the USA.

The definition of the source sample is given here. Click on the J2000 IAU name (in the left column) or the alternative name (mostly B1950 IAU names, in the right column) to get more information on a source, including coordinates, redshift, VLBApls images and model components.

• Caltech-Jodrell Bank Survey (1.6, 5 GHz)
• VLBA Calibrators Survey (2.3, 8.4 GHz)
• US Naval Observatory, Radio Reference Frame Image Database (2.3, 8.4, 15 GHz)
• VLBA 2-cm Survey (15 GHz)

• University of Michigan radio flux density monitoring
• GBI-NASA monitoring program
• VLA Calibrator Manual
• VLA FIRST Survey (1.4 GHz)
• NRAO VLA Sky Survey (NVSS) (1.4 GHz)