History of the Observatory:
Robert Baker, author and star counter (1923-1951)
Robert Horace Baker (1883-1964) succeeded Stebbins as the third director of the Observatory. Baker was born in Massachusetts in 1883 and conducted his graduate work in astronomy at the University of Pittsburgh where he was an assistant at the Allegheny Observatory. He received his Ph.D. in 1910 and spent the next 10 years as a professor at the University of Missouri. Baker arrived in the fall of 1923, after a year as Kellog Fellow at Lick Observatory. There, he gained experience with the photo-electric photometer patterned after Stebbin's 1915 photometer.
Baker was a logical choice for the next director because of his experience with photometry and working with modest size telescopes. Baker and the first Illinois Ph.D. graduate C.C. Wylie (who remained until 1925) continued to use the photometer on the 12-inch refractor to search for eclipsing binary stars. By 1925, they announced the discovery of three more new eclipsing binaries. The photometer was also used to help develop an improved photometer for use on the rebuilt 30-inch reflector.
Baker had a problem, what to do with the 30-inch reflector. The site was no-longer suitable because of the bright sky and the telescope's performance was poor. Baker was able to secure funding from the University in 1925 to move the observatory and have it rebuilt. Since the Brashear mirror had proven unsatisfactory, a new mirror was ordered. The new primary mirror was 29 ½ inches in diameter, 4-inches thick with a 4-inch hole in the center figured by John E. Mellish. The new focal length of the primary was 75-inches and the focal ratio of the Cassegrain system was 12. The 30-inch observatory's new site was on the south side of Florida Avenue, just east of Wright Street, about a quarter mile south of the Observatory. The site had darker skies courtesy of a cemetery to the north and crop fields to the south. When completed in 1927 the new observatory was frequently referred to as the South Observatory.
The rebuilt telescope was complemented by a new photometer built by the J.B. Hayes Company of Urbana. They had assisted Stebbins with older photometers. The new photometer featured two cells and electrometers side by side. Light could be diverted to either side. The cells were manufactured by the Copper-Hewitt Company, but filled by Kunz. The electrometers were patterned after the Lick Observatory's electrometers. As the photometer was used more, it was found not to perform as well as hoped. To improve its performance, a single photocell by Kunz replaced the two Copper-Hewitt cells and the dual electrometer was replaced by a smaller Lindemann electrometer. The photometer was used in routine observations of suspected variable stars and for instruction. Sidney Jacob Walck (A.B. from Baldwin-Wallace College 1927) earned his Masters degree in 1930 for his thesis "Photoelectric Photometry in Astronomy." Robert B. Arnold earned his Masters in 1931 for his thesis work "The Design and Use of a Photoelectric Photometer for Astronomical Research."
The 30-inch's typical routine was broken in 1933 with the opening of the Chicago World's Fair. At a quarter past nine o'clock on the evening of 27 May 1933, the telescopes at Yerkes, Harvard, Allegheny and the 30-inch of the University of Illinois, with photocells attached, were pointed at Arcturus. When the light of Arcturus, which left the star in 1893 during the last Chicago World's Fair, reached the photocells, a circuit was completed. "Instantly upon that contact the ground, pavilions and waterways of the fair were drenched with light. Thousands of awed beholders broke into cheers. The jubilation blended into the harmony of the national anthem. Bands, bells, choruses and a symphony orchestra filled the plazas, promenades and palaces with music." (New York Times)
During the Thirties Baker's interests changed to writing. He felt the heavens were meant for everyone to see and wonder about, and it was the role of the astronomer to make things that go on up there understandable to everyone. Baker was an extremely gifted writer whose clear simple work helped him explain what was going on up there to an entire generation. In 1930, he authored the textbook Astronomy, followed in 1932 by The Universe Unfolding, and his revision of Simon Newcomb's Astronomy for Everyone. In 1934 Baker described an imaginary trip to the moon in When the Stars Come Out. His second textbook, An Introduction to Astronomy also appeared in 1934. Introducing the Constellation was published in 1937 and, with the help of Howard Zim in 1951, Stars: A Guide to the Heavens. His textbooks were used across the entire country for undergraduate astronomy courses and praised as classics. His books were extremely successful with each edition going through numerous printings.
In 1931-1932 and again in 1938-1939, Baker took sabbatical leaves to serve as Research Associate at Harvard. It was at this time he became involved with the work of Bart Bok, who was beginning his star counting circuit. Bok's circuit involved the counting of stars in the Milky Way down to the fifteenth magnitude in order to achieve an understanding of the distribution of stars in the Milky Way. Even though photographs had been taken at the prime focus of the 30-inch, it was not suited for such work. Baker contacted the J.W. Fecker Company about adapting the telescope to make it suitable for photography. In the fall of 1939, a new photographic telescope was in place. It was a 4-inch Ross-Fecker photographic refractor. The instrument was an f/7 and held 8x10 inch glass plates covered 9.4 x 4.4 degrees of sky. Baker and his students, which included Elaine Nantkes, Lois Kiefer, David Heeschen and Alan Sandage, published 7 papers in the Astrophysical Journal on the analysis of the Milky Way in Cassiopeia, Ophiuchus, Sagittarius, Auriga, Aquila, Cepheus and Perseus. Kiefer earned her Ph.D in mathematics for her work on radial analysis of the structure of the Milky Way while Heeschen earned his Masters for his work on Perseus. Undergraduate Alan Sandage learned the skills that he credits with making him an astronomer today. This was the principal research in astronomy done at the University of Illinois from 1939 until 1951.
Astronomy suffered during the Baker years due to international events. The department’s budget for equipment and salaries changed little during the Roaring Twenties, but the Thirties brought the Great Depression. The budget tumbles from $1,000 a year to just $200, less then Stebbins had received twenty years earlier. As the Depression eased, the budget slowly grew to $640 in 1941. With the involvement of the United States in the World War, the budget again declined. After the War, the budget slowly grew, but during Baker's last year it never reached the same level as in 1920.
Bakers last years at the Observatory were more languid. He taught only a few descriptive astronomy classes and spent most of his time updating his textbooks. While the Ross camera was kept in good condition, the 12-inch refractor and transit were used only occasionally, mostly for public nights and school groups. When other astronomy departments were expanding, the Illinois program was stagnating. Baker was only able to keep the Observatory clocks running. Baker retired in the fall of 1951. Perhaps the greatest tribute that can be paid to Dr. Baker is not a listing of awards and tributes, but rather the gratitude of an entire generation of amateur and professional astronomers who owe their interest in the stars to a book authored by Robert H. Baker.