History of the Leander McCormick Observatory

The Observatory was founded through a $68,000 gift from Leander J. McCormick, the brother of Cyrus McCormick, in 1877. The McCormick family had settled in the Shenandoah Valley, and in 1831 the brothers and their father invented the mechanical reaper, which made the family fortune. The gift was first offered to Washington College, but its president, Robert E. Lee, declined the offer, partly on the grounds that continuing support for the Observatory would be difficult to provide. Charles Venable of the Mathematics department led the effort to bring the Observatory to the University and arranged a $75,000 endowment from Commodore Vanderbilt and others.

For several years the 26-inch refractor was the largest telescope in the country. Although later surpassed in size, the McCormick lens is still regarded as the most perfect large lens ever produced. The telescope was the first major scientific facility at the University of Virginia.

Nonetheless, Lee's reluctance proved to be well founded. It is fair to say that the University did not take advantage of the Observatory by providing enough support to guarantee its continuing eminence, unlike a number of other universities with comparable facilities. In fact, for the first 35 years of its existence, the Observatory did not receive any support from the University. Instead it had to rely completely on the small income from its endowment for both salaries and operating costs, and there was only one position for a Ph.D.-level astronomer.

Under the energetic leadership of S. A. Mitchell, its second director and one of the first University faculty members to be elected to the National Academy of Sciences, the Observatory became more active and trained a number of leading astronomers. One of its early PhD's was H. D. Curtis, who later participated in the famous debate with Harlow Shapley over the scale of the universe (Curtis was right, but Shapley had better arguments). Mitchell began an extensive program of photographic astrometry, which became the Observatory's most important historical contribution to astronomy, in 1914. He also undertook research collaborations with major centers such as Harvard, Columbia, and Mount Wilson Observatory and enthusiastically led a number of solar eclipse expeditions. Mitchell arranged a small amount of additional continuing support from the McCormick Estate and other outside sources. State-supported positions were first provided for astronomy in the 1920's, though no more than three faculty positions were made available before 1960.

Following a thorough assessment of the Observatory's prospects by a blue-ribbon panel in the early 1960's, L. W. Fredrick became Director in 1963 and led the Observatory and Astronomy department through a phase of rapid expansion in facilities, staff, and student enrollments. The 26-inch telescope was repaired and modernized, major NSF and NASA funding was obtained, a new state-of-the-art measuring engine for photographic plates was purchased, and plans were made to build a new observatory outside of Charlottesville that would be protected from the increasing problem of light pollution in the city.

The Fan Mountain site was selected, and by 1965 two telescopes were operating at Fan: the 10-inch astrograph, a wide field refractor which was moved from McCormick Observatory, and a new, general purpose 30-inch reflector manufactured by the Tinsley Corporation. Plans for the 40-inch astrometric reflector, intended to replace the 26-inch in the long term, were completed by 1969, and site preparation began late that year. The telescope was completed in the mid-1970's. With three telescopes in the 26-40-inch class operating at two separate sites, the Observatory is the largest concentration of optical telescopes in the eastern US.

In 1965, the scientific headquarters of the National Radio Astronomy Headquarters was moved to Charlottesville, adjacent to the University. This had a very beneficial impact on the scientific atmosphere for astronomy and was a key to recruiting good faculty for the Astronomy department. The staffing strategy adopted was to emphasize fields which complement, rather than duplicate, the expertise represented by NRAO. The Astronomy department was also included in the University's Center of Excellence proposal to NSF in 1964 and has benefitted greatly over the years from its association with the Center for Advanced Studies. In 1985, the Virginia Institute for Theoretical Astronomy opened under the auspices of the Astronomy department, with University, NSF, and NASA support.

By 1988, the department had grown to 15 faculty positions. Aside from astrometry, the present emphasis is on theoretical astrophysics and extragalactic astronomy. With a semesterly enrollment of 1000 undergraduates, the department teaches (on a statistical basis) an astronomy course to every student in the College of Arts and Sciences during his/her career. The mean number of enrolled graduate students is 20. The Observatory also sponsors a regular Public Night program, which attracts some 3000 visitors each year.

Astrometric Programs at the Observatory

Mitchell undertook an extensive photographic program with the 26-in starting in 1914 because it had been demonstrated in the preceding decade that astrometric accuracies far superior to visual ones could be obtained with multiple photographic exposures. At that time, the true distances of only about 100 stars were known, and the determination of stellar distances by the trigonometric parallax method was one of the most compelling and challenging problems in astronomy.

The parallax program which Mitchell initiated has been extremely successful. Although more than a dozen important observatories have been active in this area, the 2300 parallaxes determined at McCormick represent about 20% of the total known prior to the launch of the Hipparchos satellite in the late 1980's. Only one other observatory has published a comparable number of accurate parallaxes. Many of the McCormick parallaxes are for nearby ``dwarf'' stars discovered by A. Vyssotsky using a special objective prism attached to the 10-in astrograph at the Observatory.

The archive of photographs taken with the 26-inch telescope now comprises about 140,000 plates. Since multiple exposures are usually taken on one plate (to save on costs), this amounts to over one-half million individual exposures. There are few comparable collections in the world.

Long-focus refractors such as the 26-inch remain useful in astrometry despite their age for two reasons. First, they are simple and stable optical systems whose characteristics are well understood through over a century of experience. Second, they produce a highly magnified image because of their long focal lengths. In the 1960's several new telescope designs optimized for astrometry but based on reflecting optics evolved. There are currently only two such telescopes in the US: a 60-inch operated by the US Naval Observatory in Flagstaff, AZ, and the 40-inch at Fan Mountain.

Astrometric programs at the Observatory in the last 20 years, under the direction of Fredrick and Philip Ianna, have concentrated mainly on parallaxes. An important secondary 26-inch program aimed at the satellites of the outer planets was undertaken in the early 1970's as support for the Voyager missions. These programs have received the strong support of NSF and NASA.

The 40-inch reflector at Fan Mountain is intended to replace the 26-inch in the long run. It is at a much darker site and provides superior images over a large field of view. Consequently, stars which are 10-100 times fainter have been placed on the parallax program for the 40-inch. The two telescopes have been simultaneously operated for several years in order that proper transformations between the two are possible. The 40-in currently utilizes both a photographic camera (for large fields) and an electronic CCD camera.

Because of its large, high quality data field, the 40-inch will be excellent for determination of the proper motions of many stars simultaneously. It is likely that emphasis in the 40-inch program will therefore shift with time toward proper motions and away from parallaxes. Star clusters are already on its observing program, and pilot projects designed to determine the feasibility of other kinds of proper motion investigations, such as the expansion of the remnants of supernova explosions, have begun.

Since 1976 Ianna has operated a parallax program using a 26-inch telescope at Mt. Stromlo Observatory outside Canberra, Australia. It is the only large astrometric program now active in the southern hemisphere and has been well supported by NSF. At least one observer from the University is resident in Australia year-round. Cooperation between the two observatories has been excellent. Emphasis in this and in the 40-inch parallax program is on stars of particular current astrophysical interest, such as white dwarf stars and ``sub-dwarfs,'' which are very ancient stars with low metal content.

Acknowledgements

The Observatory gratefully acknowledges the continuing support offered, collectively and individually, to our staff by the Estate of Leander J. McCormick, the National Science Foundation, the National Aeronautics and Space Administration, the Air Force Office of Scientific Research, and the University of Virginia.


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