VLBA Images -- `snapshot' images made using the National Radio Astronomy Observatory (NRAO) Very Long Baseline Array (VLBA) telescope. Images using the VLBA together with several geodetic antennas are also available for some sources. These 'VLBA+' images provide enhanced uv-plane coverage and up to twice the resolution of the VLBA alone. Available items include contour plots and visibility plots in PostScript format. Images and/or visibility data can also be obtained in FITS format upon request. Geodetic VLBI Images -- `snapshot' images made using geodetic and/or astrometric Very Long Baseline Interferometry (VLBI) observations. Available items include contour plots in PostScript format.

The data presented here are the result of an ongoing program to image radio reference frame sources on a regular basis. Our goal is to establish a database of images of all of radio reference frame sources at the same wavelengths as those used for precise astrometry (13cm and 4cm). These data will allow us primarily to monitor sources for variability or structural changes so they can be evaluated for continued suitability as radio reference frame objects. Further information concerning these data can be found in the following publications:

1. "VLBA Observations of Radio Reference Frame Sources. I.,"
   Astrophysical Journal Supplement Series, August 1996 issue (Vol. 105, No. 2, Pages 299-330).

2. "VLBA Observations of Radio Reference Frame Sources. II. Astrometric Suitability Based on Observed Structure,"
   Astrophysical Journal Supplement Series, July 1997 issue (Vol. 111, No. 1, Pages 95-142).

3. "VLBA Observations of Radio Reference Frame Sources. III. Astrometric Suitability of an Additional 225 Sources,"
   Astrophysical Journal Supplement Series, May 2000 issue (Vol. 128, No 1, Pages 17-83).

If you make use of these data in any publication, please refer to the citation instructions.

VLA and VLBI images of many of these sources may also be obtained from the Pearson-Readhead and Caltech-Jodrell Surveys. See also the VLBA Calibrator Survey and the VLBA 2cm Survey.