The Caltech VLBI Programs

There are three parts to the Caltech VLBI programs.

1. Caltech VLBI Analysis Programs

For a description, see Caltech VLBI Analysis Programs by T. J. Pearson [Bull. Amer. Astron. Soc., 23, 991-992 (1991).] These programs are written in Fortran, and run on Sun workstations (SunOS or Solaris).

Most of the programs are now obsolete, and no further work is planned. It is not recommended that new users attempt to use the programs.

The programs are limited to single-channel data (single frequency, single IF, single polarization), and the data files use a non-extensible, non-portable (machine-specific) format (the MERGE format). Users should convert old MERGE-format data to UV-FITS using the program MERGEFITS. The UV-FITS format is completely portable and can accommodate multi-IF, multi-polarization, and spectral-line data. Files in this format can be processed using Difmap (version 2.0 or later) and AIPS, as well as other systems.


Source code


You will also need the Fortran version of the SLALIB library written by Patrick Wallace ( of STARLINK. This is available from the Starlink Software Store.


The VLBI scheduling program, SCHED, is now distributed by NRAO:

For convenience of Caltech users, a local copy of the documentation is available (only on the Caltech Astronomy Solaris machines) - last updated December 6, 1998:


This is an interactive mapping program that replaces many of the Caltech VLBI analysis programs. It is written in ANSI C, and runs on Sun, IBM, and HP workstations and possibly other UNIX workstations with X-window graphics. For a description, see DIFMAP: an interactive program for synthesis imaging by M. C. Shepherd, T. J. Pearson, and G. B. Taylor [Bull. Amer. Astron. Soc., 26, 987-989 (1994); Bull. Amer. Astron. Soc., 27, 903 (1995).]; and DIFMAP: an interactive program for synthesis imaging by M. C. Shepherd [ASP Conference Series, vol.125, "Astronomical Data Analysis Software and Systems VI"].

DIFMAP is obtainable by anonymous ftp from An introductory users' guide is available in the Cookbook.

3. PGPLOT Graphics Subroutine Library

Both (1) and (2) require the PGPLOT Graphics Subroutine Library.

For further information, contact: