VLBI Observations

The VLA can now participate in VLBI observations with the VLBA.  Currently, this is only allowed in phased array mode (i.e. single dish is not allowed) with highly restricted WIDAR correlator configurations.   For more details see the VLBI at the VLA documentation.  In phased array mode the program TelCal derives the antenna-based delay and/or phase corrections needed for antenna phasing in real time.  This delay correction is then applied to the antenna signals in the correlator and the visibilities are then summed.  The resulting phased array sum is recorded in VDIF format on the Mark5C recorder at the VLA site.  The disk(s) are then transported to Socorro, NM and correlated on the DiFX correlator with other VLBI stations which participated in the observation.  The standard WIDAR data are also archived in the NRAO science data archive.

Connect with NRAO

The National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

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