NRAO-GBI previous operations.

Recent operations (1989-1996) of the GBI were funded by the US Naval Observatory (USNO) and included:

• Geodetic VLBI using 85-3 only. Weekly observing runs as part of the Navy Network (NAVNET) contribute to the National Earth Orientation Service (NEOS). This project moved to the new 20-meter telescope in 1995. The 85-3 telescope has participated in collecting data for the new high-precision Radio-Optical Reference Frame (RORF) for the Naval Research Lab (NRL) and the USNO.
• Pulsar monitoring using 85-3 only. Pulsar observing schedule. A group at Princeton and Oberlin use these data to study (a) timing changes (or "glitches"), which provide clues to the internal structure of pulsars, and (b) brightness variations, which provide information about gas cloud and magnetic field structure in the interstellar medium. The pulsar program is continuing, using antenna 85-3 only, with temporary support from NASA.
• Variable source monitoring using 85-1 and 85-2. Flux density measurements are made of selected galactic and extragalactic radio sources for the astronomy group at NRL. Extreme scattering events, caused by intervening scattering clouds, were discovered in 1987. Well-known binaries such as Cygnus X-3 and SS433 have been monitored for years. Additional X-ray binary stars have been added in the recent 2-3 years, for comparison with x-ray satellite observations. This project stopped in April 1996 due to lack of funding, but has been revived in November 1996 with funding from NASA.

Earlier operations included:

• Aperture synthesis imaging for astronomy, run by NRAO. (1964-1978)
• Earth orientation and timing for USNO (1978-1988)

Smaller dishes at remote locations were part of the Interferometer but have since been moved or dismantled:

• 42-foot telescope on Spencer Ridge. (1969-1972)
• 45-foot telescope near Huntersville, WV (used 1973-1983). Moved in 1988 to Green Bank to become a tracking station for Orbiting VLBI satellites.
• 46-foot telescope on Point Mountain, WV (used 1983-1988). Ownership transferred to NOAA and moved to Fortaleza, Brazil in 1991-92 for use in geodetic VLBI.