The Harvard Radio Astronomy Station at Fort Davis, Texas

The Harvard Radio Astronomy Station at Fort Davis, Texas, came into operation in 1956 as a radio extension of the U.S. Air Force Sacramento Peak Observatory. The location near Fort Davis was chosen for the low level of man-made radio signals. Initially the receiving equipment at the site included a 28-ft diameter antenna and covered the range 100-580 MHz. The receivers swept through this band approximately three times per second, recording the spectrum of solar radio activity. In subsequent years the frequency range was extended to cover all or parts of 10 MHz to 4 GHz. All recorded solar bursts were identified according to five principal spectral types, and lists including times, durations, and frequency ranges of all solar activity were published. Studies of the bursts included analyses of their relationships to flares and other optical solar phenomena, and also their relationships to geophysical phenomena, including magnetic storms and polar blackouts. An 85-ft diameter antenna was installed in 1963, which during 1970-1974 was used for solar observations in the range 580 MHz to 4 GHz. Otherwise this antenna was used for non-solar radio astronomy, including lunar occultations of radio sources, measurements of flux densities at 5 GHz, investigations of the Galactic Center, and similar projects. The solar program was closed in late 1982 after 26 years of continuous operation. After 1974 the 85-ft antenna was used mainly in a program of VLBI network observations conducted by astronomers from Caltech and NRAO. In 1991 it was replaced by an antenna of the VLBA program of the NRAO. This paper describes some details of the antennas and receivers, and results of the solar studies. It also includes a brief discussion of the non-solar observations other than the VLBI program.