Frank E. Ross

Frank Elmore Ross, who served as the first secretary of OSA, was born April 2, 1874, in San Francisco. In 1896, he earned a B.S. from the University of California, where he majored in astronomy and geodesy. After teaching for a year, he returned to Berkeley as a Fellow in mathematics. Specifically, he studied celestial mechanics and the determination of planetary orbits. In 1898, he became a Fellow in astronomy at the Lick Observatory.

As early as 1894, he photographed the transit of Mercury. He completed his Ph.D. in mathematics at Berkeley in 1901, but his interests—and his entire subsequent career—were devoted to astronomy. The following year, he moved to the Nautical Almanac office in Washington, D.C., and by 1903 he had become the chief assistant to Simon Newcomb, who was working out new, definitive orbits of all the planets. Ross was a master of manipulating mathematical formulae, as well as fast, practical, accurate numerical calculations (long before the days of electronic computing).

After Newcomb’s death in 1909, Ross became director of the International Latitude Observatory at Gaithersburg, Md. While there, he invented and developed a photographic zenith tube, which greatly improved the accuracy of the measurements of systematic variations of the declinations of stars. In 1915, he became a research physicist at the Eastman Kodak Laboratory in Rochester, N.Y., where he studied the developing, fixing, washing and drying of photographic images of stars and how to measure stellar positions as accurately as possible.

He also began work on optical design, which required much the same mathematical skills as orbit determinations. As an optician, he introduced the wide-angle lens as an important photographic tool in astronomy. During World War I, he designed a large-field fast camera for aerial photography and invented what later became known as the Ross lens. It is a four-lens optical system, which was a great improvement over the earlier Cooke triplets used for wide-field photography. Most of his publications were in journals of astronomy. However, in 1918 he wrote a book called The Physics of the Developed Photographic Image.

In 1924, Ross left Rochester and joined the faculty of the Yerkes Observatory of the University of Chicago. There he repeated, with the 10-in. Bruce photographic telescope, direct photographs of the same fields that his predecessor, Edward Barnard, had taken years before. Comparing these pairs of photographs with a “blink microscope,” which shifts the view back and forth between two photos of the same field, Ross discovered many stars with unusually large angular motion in the sky: high proper motion stars.

He detected a new type of variable star in 1925. In the period between 1925 and 1931, he carefully photographed areas of stars and compared his findings with other published data. He compiled 10 lists of variable stars (379 altogether), and published them in the Astronomical Journal. The stars are now called Ross variables, and his lists were still being re-examined and corrected as recently as 2004. In 1927, he turned his attention to a curious star with a high proper motion. He named it the Witches Head Nebula. It is now called Binary Star Ross 614. He compiled an atlas of the Northern Milky Way.

In 1928, Ross went to Pasadena as the chief optical designer for the 200-in. telescope project. His first task was to design a correcting lens system to be used near the focus of the 200-in. primary mirror to remove the inevitable aberration of “coma” (the natural unsharpness of the images that are not at the center of the field).

He succeeded in designing such a system, now called the Ross corrector lens. He consulted for other observatories; for example, in 1936, he designed corrector lenses for the Cook Astrograph of the University of Pennsylvania. He retired from Yerkes in 1939, and from the 200-in. project in 1942, but he kept an office in the Mount Wilson Observatory headquarters. Ross was elected to the National Academy of Sciences.

He died in Altadena, Calif., in 1960.