University of Illinois Observatory
Encyclopedia
The University of Illinois Astronomical Observatory was constructed in 1896. It stands on South Matthews Avenue in Urbana
, Champaign County, Illinois
. The observatory was listed on the National Register of Historic Places
on November 6, 1986 and on December 20, 1989, the U.S. Department of Interior designated the observatory a National Historic Landmark
. Though none of the astronomical instruments are being used for professional research today, the observatory still contains a 12" Brashear
refractor
. The observatory played a key role in the development of astronomy as it was home to a key innovation in the area of astronomical photometry
. The facility has been directed by such noted scientists as Joel Stebbins
and Robert Horace Baker
.
Erected in 1896 at the behest of the Illinois General Assembly, the University of Illinois Observatory became important in the development of astronomy
due, in large part, to pioneering research by Stebbins, from 1907 to 1922. Joel Stebbins left the University of Illinois in 1922 but left behind a legacy of discovery that helped alter the face of modern astronomy. The building, itself, is in a traditional observatory
design, Colonial Revival style, following a T-plan. The dome rises 35 feet (10.7 m) in the air. The building served the University of Illinois astronomy department from its opening until 1979, when the department moved into a new, larger building to house its growing staff.
, the legislation provided $15,000 to build the building. The site chosen was a grass knoll between Matthews Avenue and Burrill Avenue, just north of the 1876 Morrow Plots
, a National Historic Landmark that is the nation's oldest experimental field. The building was constructed to replace an older and smaller observatory on campus. Contracts were extended to Charles A. Gunn, the architect, and Bevis and Company in Urbana as the general contractor in the spring of 1896 and construction began in April. The building was completed by August at a total cost of $6,800.
The first director of the observatory was G.W. Myers. In his first year as director, G.W. Myers announced the discovery of the source of the variability in the star Beta Lyrae
. He served as director from 1897 until 1900 when he left for the University of Chicago
. W.C. Brenke, an astronomy instructor, served as acting director until a new director was hired in 1903.
Before 1907, all magnitude measurements for stars were obtained through visual comparison of relative brightness
, a process that was slow and inexact. Later, after 1907, photographic methods would use starlight to make a representation on a photographic plate. Regardless, neither method was adequate for quantitative measurements. The drawback of previous methods of measuring stellar magnitude made the use of electricity for empirically gathering astronomical data revolutionary for the science of astronomy
. Joel Stebbins
' pioneering research for astronomical photometry took place at the observatory.
Stebbins arrived as director of the University of Illinois Observatory after he completed his Ph.D. at the University of California, Berkeley
in 1903. His key research took place between the years 1907 and 1922. Once Stebbins arrived, in 1903, from Lick Observatory
, he began to study the brightness of 107 binary stars using a Pickering visual photometer. The research, with the assistance of his wife, May Stebbins, investigated the relative brightness on binary stars using visual techniques. In a 1957 speech at the American Astronomical Society
, Stebbins recalled the events which led up to the electric cells:
Stebbins and Brown soon became friends and in time, they had a selenium cell
positioned on the 12 inches (304.8 mm) telescope at the observatory. In the fall of 1907, after several attempts, the two achieved a light curve
for Earth's moon. Their successful use of photoelectric technology was a huge leap for astronomers. Later Stebbins went further, discovering that by cooling the cell to zero degrees Fahrenheit he would double the cell sensitivity and diminish irregularities in the circuit tenfold, still further, by reducing the size of the cell the irregularities were reduced more. The pair went on to detect stellar intensity and activity that were previously unrecorded. By 1907 when Stebbins and Brown used the selenium cells to observe the brightness of the moon, including a July Lunar Eclipse
, discoveries of astronomical sigificance began to become commonplace at the observatory. In 1907 Stebbins and F.C. Brown used the selenium cells to study the brightness of the Moon. This marked the first time in America that electricity was used to measure astronomical brightness. The coming of Comet Halley
in 1910 allowed Stebbins, in May, to use his selenium photometer to study the comet. Two years later Stebbins used the photometer
and discovered four stars to be eclipsing binary stars: Beta Aurigae
, Spica
, Alpha Coronae Borealis and Delta Orionis
.
Stebbins pioneering work with the selenium
cell continued until 1913, when he and University of Illinois physics professor Jakob Kunz became associated. Kunz had been doing experimentation on an improved photoelectric cell which was alkali
based. Kunz's cell was the predecessor of the modern day "electric eye
." A number of other notable astronomical discoveries occurred at the observatory through the years. In 1915 Stebbins' object of study became the star involved in Myers' first big discovery at the observatory, Beta Lyrae. A solar eclipse
on June 9, 1918 gave Stebbins and physicist Jakob Kunz the chance to observe from Wyoming using the photometer.
After numerous discoveries, Stebbins left the University of Illinois in 1922, the same year that Charles Wylie
earned the first U of I doctorate in astronomy. Stebbins left for the Washburn Observatory
in Wisconsin and Dr. Robert H. Baker took over as the new Director of the University of Illinois Observatory. However, because the observatory lost its pioneering researcher in Stebbins did not mean that discovery and science did not continue at the university's observatory.
When Robert Baker arrived he continued a photoelectric photometry program focusing on variable stars. He had a new photometer constructed and attached it to the 30-inch reflector telescope in the Observatory annex. He supervised two graduate students who worked on this equipment in the early 1930s. On May 27, 1933 the star Arcturus provided light which fell onto a photo cell in the observatory's annex and sent a signal to open the Chicago World's Fair
.
The Great Depression was soon in full swing. and the department budget fell from $1000 to a mere $200. It was during this time that Dr. Baker authored a number of books. 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.
After two sabbaticals to Harvard, Baker's interest moved from photometry to the Milky Way. In 1939 the 30-inch reflector was replaced with a Ross photographic telescope and for more than ten years after that, 1939 through 1951 Baker used the observatory's photographic telescope to help count the stars in the Milky Way and determine their distribution as part of Harvard's Star Counting Circuit.[6] This would be the primary research until Baker's retirement in 1951. The 12-inch refractor was only used for instruction, public open houses and for visiting school groups.
On October 4, 1957, the very evening of the launch of Sputnik, students and faculty met at the Observatory and constructed an improvised radio interferometer. They published the first precise ephemeris in Nature in November. In 1961, as the Space Race
heated up, Senator Paul H. Douglas
requested that the membership of the American Astronautical Society
be polled by the University of Illinois Observatory as to the "scientific value" of the U.S. plan to land on and return one or more men from the Moon
.
The observatory is no longer used for research purposes, though the telescope is still used as a teaching tool in the university's astronomy classes. In addition, a University of Illinois student astronomy organization uses the telescope. The observatory dome underwent a renovation that included repainting in 1996.
The observatory was built on a one story T-plan, facing north, of buff-colored Roman brick
(from Indiana
) and features limestone
lintels and sill
s. The cross of the T is 75 feet (22.9 m) long east to west and 25 feet (7.6 m) deep, its stem is located to the south, centered along the east-west axis and is 26 feet (7.9 m) deep by 25 feet (7.6 m) wide. The octagonal observation tower
rises 25 feet (7.6 m) into the air at the intersection of the T where it becomes a dome and continues to a height of 35 feet (10.7 m). At floor level of the second equatorial room
a balustrade
circles around the exterior of the tower. The tower is capped by a great circular limestone plate, which carries the dome track. Internally, the diameter of the dome is 24.5 feet (7.5 m) and its zenith 24 feet (7.3 m) above the floor. The dome slit, which still operates, has an opening of 44 inches (1,117.6 mm) and can be opened or closed by hand in seconds. The dome tower and equatorial room
are original save a motor drive which replaced the old rope and sheave method of rotating the dome.
In the center of the equatorial room is the 1896 12 inches (304.8 mm) refractor telescope. Built by the firm of Warner and Swasey, Cleveland, Ohio
, the scope is stabilized on a brick pier which extends down into the bedrock and is not attached to the building in any way. The telescope cost $4,500 and still has the original observer's chair mentioned in the contract with Bevis and Company at a cost of $25. The entrance hall, below the equatorial room
, octagonal in shape, is centered around a brick pier. The entrance hall retains original stairs, newel posts, balustrades, and wood floors; it is still used for its original purpose, storage.
The east and west wings of the building once each contained a transit room. Each of the rooms had a mounted transit telescope on a brick pier; the piers are still visible in the basement below the transit rooms. The western transit rooms were converted into office space by the 1920s. The eastern transit rooms were converted to office space more recently.
The exterior of the observatory building has a brick cornice
, with stone sills and lintels, stone water course, ornamental gutters, and original copper downspouts. Most of the building's windows are of the wooden double-hung
variety and original, as are the front entrance door transom and concrete stoop. The original front balustrade has been replaced, however, the western stoop and ornamental iron balustrade is still original.
Aside from the transit room conversion to office space the building has seen other major work in the past. The southwest corner of the building was built in 1956, of cream colored brick, to house additional classrooms and office space. The addition of 1956 took special care to replicate nearly every aspect of the original building except for color. Another major addition occurred in 1966 with the construction of the large east wing. Of the same cream colored brick as the 1956 addition, it also tried to mimic the building's finer details. The 1966 east wing addition provided for, again, more office space, but this project also included space for a new darkroom
and a radio telescope
laboratory. The observatory basement and the dome housing the refractor are still in use by the astronomy department at U of I and the University of Illinois Astronomical Society, a student organization on campus.
It is mounted on a rectangular cast-iron column of two-tons weight that rests on the masonry pier. Through a glass door in the column you can see the driving clock that keeps the telescope turning westward just as fast as the stars go, so that a star remains in view as long as the astronomer wishes to observe it. The telescope turns on two axes at the top of the column. One axis slants upwards toward the north pole of the heavens; the other at right angles to it, and it is to this one that the tube of the telescope is attached. Two large circles provide graduated scales for locating objects by their coordinates. The instrument can be turned on these axes toward any part of the sky. It is a heavy instrument, but so perfectly balanced that the astronomer moves it easily with one hand.
The principle transit circle was a 3-inch Combined Transit and Zenith telescope designed by Warner & Swasey especially for Illinois. The objective, by John Brashear, was held in place by a special cell that compensated for the different temperature conductivities of the brass and glass so that temperature had no effect on the location or separation of the lenses. Designated as model M-505, the transit included a handing level, micrometer and a built in reversing mechanism. This transit was located in the east-central transit room allowing direct access to the clock room through a small window. The instrument cost $1200 in 1896.
The transit circle was capable of determining both right ascension and declination of a star, unlike the more simple and common transit instrument that can only determine the right ascension. Such an instrument could also be used to set the Observatory’s clocks by observing standard stars whose position was precisely known.
In addition there were three other smaller transit telescopes, a sidereal clock by Riefler, and other accessories including sextants, chronometers, and teaching tools.
photoelectric cell
. The cell revolutionized the science of astronomical photoelectric
photometry
. This branch of astronomy measures stellar magnitude. The research regarding photometry was conducted on a 12 inches (304.8 mm) Warner and Swasey
refractor telescope in the second-story equatorial room. The selenium cell was developed by Joel Stebbins
from 1907 to 1922 while he directed the observatory. As a result of Stebbins' work determining stellar magnitude using photoelectric photometry, it became standard technique. Due to this astronomical importance the observatory was listed on the National Register of Historic Places
on November 6, 1986 and on December 20, 1989 the U.S. Department of Interior designated the U of I Observatory a National Historic Landmark
.
Urbana, Illinois
Urbana is the county seat of Champaign County, Illinois, United States. As of the 2010 census, the population was 41,250. Urbana is the tenth-most populous city in Illinois outside of the Chicago metropolitan area....
, Champaign County, Illinois
Champaign County, Illinois
Champaign County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 201,081, which is an increase of 11.9% from 179,669 in 2000.. It is the 10th most populous county in Illinois...
. The observatory was listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
on November 6, 1986 and on December 20, 1989, the U.S. Department of Interior designated the observatory a National Historic Landmark
National Historic Landmark
A National Historic Landmark is a building, site, structure, object, or district, that is officially recognized by the United States government for its historical significance...
. Though none of the astronomical instruments are being used for professional research today, the observatory still contains a 12" Brashear
John Brashear
Dr. John Alfred Brashear was an American astronomer and instrument builder.- Life and work :Brashear was born in Brownsville, Pennsylvania, a town 35 miles south of Pittsburgh along the Monongahela River. His father, Basil Brown Brashear, was a saddler, and his mother, Julia Smith Brashear, was a...
refractor
Refracting telescope
A refracting or refractor telescope is a type of optical telescope that uses a lens as its objective to form an image . The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used for long focus camera lenses...
. The observatory played a key role in the development of astronomy as it was home to a key innovation in the area of astronomical photometry
Photometry (astronomy)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation...
. The facility has been directed by such noted scientists as Joel Stebbins
Joel Stebbins
Joel Stebbins was an American astronomer who pioneered photoelectric photometry in astronomy. He earned his Ph.D at the University of California. He was director of the University of Illinois Observatory from 1903 to 1922 where he performed innovative work with the selenium cell...
and Robert Horace Baker
Robert Horace Baker
-Biography:Robert Horace Baker was born on March 29, 1883 in Northampton, Massachusetts, the son of Horace Hall Baker and Ellen H. Puffer. He died in a hospital in Upland, California on June 23, 1964. Educated at Amherst College, he graduated with an A.B. in 1904 and A.M. the following year...
.
Erected in 1896 at the behest of the Illinois General Assembly, the University of Illinois Observatory became important in the development of astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
due, in large part, to pioneering research by Stebbins, from 1907 to 1922. Joel Stebbins left the University of Illinois in 1922 but left behind a legacy of discovery that helped alter the face of modern astronomy. The building, itself, is in a traditional observatory
Observatory
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geology, oceanography and volcanology are examples of disciplines for which observatories have been constructed...
design, Colonial Revival style, following a T-plan. The dome rises 35 feet (10.7 m) in the air. The building served the University of Illinois astronomy department from its opening until 1979, when the department moved into a new, larger building to house its growing staff.
Early history
The Illinois state legislature voted in 1895 to fund a new observatory at the University of IllinoisUniversity of Illinois at Urbana-Champaign
The University of Illinois at Urbana–Champaign is a large public research-intensive university in the state of Illinois, United States. It is the flagship campus of the University of Illinois system...
, the legislation provided $15,000 to build the building. The site chosen was a grass knoll between Matthews Avenue and Burrill Avenue, just north of the 1876 Morrow Plots
Morrow Plots
The Morrow Plots is an experimental corn field at the University of Illinois at Urbana-Champaign and is the oldest of its kind in the Western hemisphere and the second oldest in the world. It was established in 1876 as the first experimental corn field at an American college and continues to be...
, a National Historic Landmark that is the nation's oldest experimental field. The building was constructed to replace an older and smaller observatory on campus. Contracts were extended to Charles A. Gunn, the architect, and Bevis and Company in Urbana as the general contractor in the spring of 1896 and construction began in April. The building was completed by August at a total cost of $6,800.
The first director of the observatory was G.W. Myers. In his first year as director, G.W. Myers announced the discovery of the source of the variability in the star Beta Lyrae
Beta Lyrae
Beta Lyrae is a binary star system approximately 882 light-years away in the constellation Lyra. Beta Lyrae has the traditional name Sheliak , from الشلياق šiliyāq, the Arabic name of the constellation Lyra.Beta Lyrae is an eclipsing semi-detached binary system made up of a B7II primary star and...
. He served as director from 1897 until 1900 when he left for the University of Chicago
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
. W.C. Brenke, an astronomy instructor, served as acting director until a new director was hired in 1903.
Stebbins' research
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
, a process that was slow and inexact. Later, after 1907, photographic methods would use starlight to make a representation on a photographic plate. Regardless, neither method was adequate for quantitative measurements. The drawback of previous methods of measuring stellar magnitude made the use of electricity for empirically gathering astronomical data revolutionary for the science of astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
. Joel Stebbins
Joel Stebbins
Joel Stebbins was an American astronomer who pioneered photoelectric photometry in astronomy. He earned his Ph.D at the University of California. He was director of the University of Illinois Observatory from 1903 to 1922 where he performed innovative work with the selenium cell...
' pioneering research for astronomical photometry took place at the observatory.
Stebbins arrived as director of the University of Illinois Observatory after he completed his Ph.D. at the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
in 1903. His key research took place between the years 1907 and 1922. Once Stebbins arrived, in 1903, from Lick Observatory
Lick Observatory
The Lick Observatory is an astronomical observatory, owned and operated by the University of California. It is situated on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, USA...
, he began to study the brightness of 107 binary stars using a Pickering visual photometer. The research, with the assistance of his wife, May Stebbins, investigated the relative brightness on binary stars using visual techniques. In a 1957 speech at the American Astronomical Society
American Astronomical Society
The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...
, Stebbins recalled the events which led up to the electric cells:
"She (May Stebbins) wrote down the numbers as the observer called them, but after some nights of recording a hundred readings just to get one magnitude, she said it was pretty slow business. I responded that someday we would do all this by electricity. That was a fatal remark. Thereafter she would often prod me with the question, "When are you going to change to electricity?" It happened that within two or three months, the Department of Physics gave an open house, and one of the exhibits was in (the) charge of a young instructor, F.C. Brown. He showed how, when he turned on a lamp to illuminate a selenium cell, a bell would ring, when the lamp was off, the bell would stop. Here was the idea: Why not turn on a star to a cell on a telescope and measure a current?"
Stebbins and Brown soon became friends and in time, they had a selenium cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
positioned on the 12 inches (304.8 mm) telescope at the observatory. In the fall of 1907, after several attempts, the two achieved a light curve
Light curve
In astronomy, a light curve is a graph of light intensity of a celestial object or region, as a function of time. The light is usually in a particular frequency interval or band...
for Earth's moon. Their successful use of photoelectric technology was a huge leap for astronomers. Later Stebbins went further, discovering that by cooling the cell to zero degrees Fahrenheit he would double the cell sensitivity and diminish irregularities in the circuit tenfold, still further, by reducing the size of the cell the irregularities were reduced more. The pair went on to detect stellar intensity and activity that were previously unrecorded. By 1907 when Stebbins and Brown used the selenium cells to observe the brightness of the moon, including a July Lunar Eclipse
Lunar eclipse
A lunar eclipse occurs when the Moon passes behind the Earth so that the Earth blocks the Sun's rays from striking the Moon. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a...
, discoveries of astronomical sigificance began to become commonplace at the observatory. In 1907 Stebbins and F.C. Brown used the selenium cells to study the brightness of the Moon. This marked the first time in America that electricity was used to measure astronomical brightness. The coming of Comet Halley
Comet Halley
Halley's Comet or Comet Halley is the best-known of the short-period comets, and is visible from Earth every 75 to 76 years. Halley is the only short-period comet that is clearly visible to the naked eye from Earth, and thus the only naked-eye comet that might appear twice in a human lifetime...
in 1910 allowed Stebbins, in May, to use his selenium photometer to study the comet. Two years later Stebbins used the photometer
Photometer
In its widest sense, a photometer is an instrument for measuring light intensity or optical properties of solutions or surfaces. Photometers are used to measure:*Illuminance*Irradiance*Light absorption*Scattering of light*Reflection of light*Fluorescence...
and discovered four stars to be eclipsing binary stars: Beta Aurigae
Beta Aurigae
Beta Aurigae , traditionally named Menkalinan, is a white subgiant ternary star system approximately 85 light-years away in the constellation Auriga.- Nomenclature :...
, Spica
Spica
Spica is the brightest star in the constellation Virgo, and the 15th brightest star in the nighttime sky. It is 260 light years distant from Earth...
, Alpha Coronae Borealis and Delta Orionis
Delta Orionis
Delta Orionis , traditionally known as Mintaka , is a star some 900 light years distant in the constellation Orion. Together with Zeta Orionis and Epsilon Orionis , the three stars make up the belt of Orion, known by many names across many ancient cultures...
.
Stebbins pioneering work with the selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
cell continued until 1913, when he and University of Illinois physics professor Jakob Kunz became associated. Kunz had been doing experimentation on an improved photoelectric cell which was alkali
Alkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
based. Kunz's cell was the predecessor of the modern day "electric eye
Electric eye
An electric eye is a photodetector used for detecting obstruction of a light beam. An example is the door safety system used on garage door openers that use a light transmitter and receiver at the bottom of the door to prevent closing if there is any obstruction in the way that breaks the light...
." A number of other notable astronomical discoveries occurred at the observatory through the years. In 1915 Stebbins' object of study became the star involved in Myers' first big discovery at the observatory, Beta Lyrae. A solar eclipse
Solar eclipse
As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and the Earth, and the Moon fully or partially blocks the Sun as viewed from a location on Earth. This can happen only during a new moon, when the Sun and the Moon are in conjunction as seen from Earth. At least...
on June 9, 1918 gave Stebbins and physicist Jakob Kunz the chance to observe from Wyoming using the photometer.
After numerous discoveries, Stebbins left the University of Illinois in 1922, the same year that Charles Wylie
Charles Wylie
Charles Clayton Wylie was the first PhD graduate from University of Illinois' astronomy department. He graduated with his doctorate in 1922 for his work "The Eclipsing Binary Sigma Aquilae, the Cepheid Variable Eta Aquilae." He remained at the University of Illinois Observatory as an instructor...
earned the first U of I doctorate in astronomy. Stebbins left for the Washburn Observatory
Washburn Observatory
The Washburn Observatory is located at 1401 Observatory Drive on the University of Wisconsin–Madison campus. Completed in 1881, it was a major research facility for about 50 years. Now it is used primarily by the public during open houses and by students in introductory astronomy...
in Wisconsin and Dr. Robert H. Baker took over as the new Director of the University of Illinois Observatory. However, because the observatory lost its pioneering researcher in Stebbins did not mean that discovery and science did not continue at the university's observatory.
Robert Baker, Third Director
Century of Progress
A Century of Progress International Exposition was the name of a World's Fair held in Chicago from 1933 to 1934 to celebrate the city's centennial. The theme of the fair was technological innovation...
.
The Great Depression was soon in full swing. and the department budget fell from $1000 to a mere $200. It was during this time that Dr. Baker authored a number of books. 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.
After two sabbaticals to Harvard, Baker's interest moved from photometry to the Milky Way. In 1939 the 30-inch reflector was replaced with a Ross photographic telescope and for more than ten years after that, 1939 through 1951 Baker used the observatory's photographic telescope to help count the stars in the Milky Way and determine their distribution as part of Harvard's Star Counting Circuit.[6] This would be the primary research until Baker's retirement in 1951. The 12-inch refractor was only used for instruction, public open houses and for visiting school groups.
Modern Department
The university decided that it was time to grow the department and hired Dr. George McVittie as the next director. After his arrival in the fall of 1952, McVittie began the refurbishment of the Observatory's major instruments. The 12-inch refractor and the 3-inch transit telescope were restored. He also began expanding the faculty. Dr. Stanley Wyatt joined the faculty in 1953, George Swenson and Ivan King in 1956, Kennth Yoss, John Dickel and James Kaler in 1964 and Edward Olson in 1966. With George Swenson's arrival, Illinois began a program of radio astronomy resulting in the Vermillion River Radio Observatory that opened in 1962. Prairie Observatory was an optical observatory consisting of a 40-inch telescope and was completed in 1967. By the time of Dr. McVittie's retirement in 1971, the one-astronomer department had expanded to nine faculty with research interests in relativity, cosmology, celestial mechanics, perturbation theory, dynamics of star clusters, planetary nebulae, planets, supernovae and radio astronomy. The department which produced only five advanced degrees prior to 1951 graduated 29 Masters and 14 Doctoral student during the McVittie administration.On October 4, 1957, the very evening of the launch of Sputnik, students and faculty met at the Observatory and constructed an improvised radio interferometer. They published the first precise ephemeris in Nature in November. In 1961, as the Space Race
Space Race
The Space Race was a mid-to-late 20th century competition between the Soviet Union and the United States for supremacy in space exploration. Between 1957 and 1975, Cold War rivalry between the two nations focused on attaining firsts in space exploration, which were seen as necessary for national...
heated up, Senator Paul H. Douglas
Paul Douglas
Paul Howard Douglas was an liberal American politician and University of Chicago economist. A war hero, he was elected as a Democratic U.S. Senator from Illinois from in the 1948 landslide, serving until his defeat in 1966...
requested that the membership of the American Astronautical Society
American Astronautical Society
Formed in 1954, the American Astronautical Society is an independent scientific and technical group in the United States dedicated to the advancement of space science and exploration. AAS supports NASA's Vision for Space Exploration and is a member of the Coalition for Space Exploration and the...
be polled by the University of Illinois Observatory as to the "scientific value" of the U.S. plan to land on and return one or more men from the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
.
Current history
The observatory underwent major renovations and additions in 1956 and 1966 to accommodate the growing faculty (see architecture section below). In 1967, the 12 inch telescope at the observatory made its last professional photometric observations. The University of Illinois' Astronomy Department moved out of the building in 1979. The same year the observatory received recognition by the National Register of Historic Places, 1986, thousands gathered at the site to observe Comet Halley's journey into the inner solar system.The observatory is no longer used for research purposes, though the telescope is still used as a teaching tool in the university's astronomy classes. In addition, a University of Illinois student astronomy organization uses the telescope. The observatory dome underwent a renovation that included repainting in 1996.
Architecture
Roman brick
Roman brick can refer either to a type of brick originating in Ancient Rome and spread by the Romans to the lands they conquered; or to a modern type of brick, inspired by the ancient prototypes...
(from Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
) and features limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
lintels and sill
Sill plate
A sill plate or sole plate in construction and architecture is the bottom horizontal member of a wall or building to which vertical members are attached. Sill plates are usually composed of lumber. It usually comes in sizes of 2×4, 2×6, 2×8, and 2×10. In the platform framing method the sill plate...
s. The cross of the T is 75 feet (22.9 m) long east to west and 25 feet (7.6 m) deep, its stem is located to the south, centered along the east-west axis and is 26 feet (7.9 m) deep by 25 feet (7.6 m) wide. The octagonal observation tower
Observation tower
An observation tower is a structure used to view events from a long distance and to create a full 360 degree range of vision. They are usually at least tall and made from stone, iron, and wood. Many modern towers are also used as TV towers, restaurants, or churches...
rises 25 feet (7.6 m) into the air at the intersection of the T where it becomes a dome and continues to a height of 35 feet (10.7 m). At floor level of the second equatorial room
Equatorial room
An equatorial room, in astronomical observatories, is the room which contains an equatorial mounted telescope. It is usually referred to in observatory buildings that contain more than one type of instrument: for example buildings with an "equatorial room" containing an equatorial telescope and a...
a balustrade
Baluster
A baluster is a moulded shaft, square or of lathe-turned form, one of various forms of spindle in woodwork, made of stone or wood and sometimes of metal, standing on a unifying footing, and supporting the coping of a parapet or the handrail of a staircase. Multiplied in this way, they form a...
circles around the exterior of the tower. The tower is capped by a great circular limestone plate, which carries the dome track. Internally, the diameter of the dome is 24.5 feet (7.5 m) and its zenith 24 feet (7.3 m) above the floor. The dome slit, which still operates, has an opening of 44 inches (1,117.6 mm) and can be opened or closed by hand in seconds. The dome tower and equatorial room
Equatorial room
An equatorial room, in astronomical observatories, is the room which contains an equatorial mounted telescope. It is usually referred to in observatory buildings that contain more than one type of instrument: for example buildings with an "equatorial room" containing an equatorial telescope and a...
are original save a motor drive which replaced the old rope and sheave method of rotating the dome.
In the center of the equatorial room is the 1896 12 inches (304.8 mm) refractor telescope. Built by the firm of Warner and Swasey, Cleveland, Ohio
Cleveland, Ohio
Cleveland is a city in the U.S. state of Ohio and is the county seat of Cuyahoga County, the most populous county in the state. The city is located in northeastern Ohio on the southern shore of Lake Erie, approximately west of the Pennsylvania border...
, the scope is stabilized on a brick pier which extends down into the bedrock and is not attached to the building in any way. The telescope cost $4,500 and still has the original observer's chair mentioned in the contract with Bevis and Company at a cost of $25. The entrance hall, below the equatorial room
Equatorial room
An equatorial room, in astronomical observatories, is the room which contains an equatorial mounted telescope. It is usually referred to in observatory buildings that contain more than one type of instrument: for example buildings with an "equatorial room" containing an equatorial telescope and a...
, octagonal in shape, is centered around a brick pier. The entrance hall retains original stairs, newel posts, balustrades, and wood floors; it is still used for its original purpose, storage.
The east and west wings of the building once each contained a transit room. Each of the rooms had a mounted transit telescope on a brick pier; the piers are still visible in the basement below the transit rooms. The western transit rooms were converted into office space by the 1920s. The eastern transit rooms were converted to office space more recently.
The exterior of the observatory building has a brick cornice
Cornice
Cornice molding is generally any horizontal decorative molding that crowns any building or furniture element: the cornice over a door or window, for instance, or the cornice around the edge of a pedestal. A simple cornice may be formed just with a crown molding.The function of the projecting...
, with stone sills and lintels, stone water course, ornamental gutters, and original copper downspouts. Most of the building's windows are of the wooden double-hung
Sash window
A sash window or hung sash window is made of one or more movable panels or "sashes" that form a frame to hold panes of glass, which are often separated from other panes by narrow muntins...
variety and original, as are the front entrance door transom and concrete stoop. The original front balustrade has been replaced, however, the western stoop and ornamental iron balustrade is still original.
Aside from the transit room conversion to office space the building has seen other major work in the past. The southwest corner of the building was built in 1956, of cream colored brick, to house additional classrooms and office space. The addition of 1956 took special care to replicate nearly every aspect of the original building except for color. Another major addition occurred in 1966 with the construction of the large east wing. Of the same cream colored brick as the 1956 addition, it also tried to mimic the building's finer details. The 1966 east wing addition provided for, again, more office space, but this project also included space for a new darkroom
Darkroom
A darkroom is a room that can be made completely dark to allow the processing of light sensitive photographic materials, including photographic film and photographic paper. Darkrooms have been created and used since the inception of photography in the early 19th century...
and a radio telescope
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
laboratory. The observatory basement and the dome housing the refractor are still in use by the astronomy department at U of I and the University of Illinois Astronomical Society, a student organization on campus.
Equipment
The primary instrument is a refractor of 12.4 inches clear aperture and of 15 ft. focal length. The optics are by John A. Brashear of Pittsburgh and the mechanical parts by the Warner & Swasey Company of Cleveland. Eyepieces provide magnification ranging from 130 to 720 power.It is mounted on a rectangular cast-iron column of two-tons weight that rests on the masonry pier. Through a glass door in the column you can see the driving clock that keeps the telescope turning westward just as fast as the stars go, so that a star remains in view as long as the astronomer wishes to observe it. The telescope turns on two axes at the top of the column. One axis slants upwards toward the north pole of the heavens; the other at right angles to it, and it is to this one that the tube of the telescope is attached. Two large circles provide graduated scales for locating objects by their coordinates. The instrument can be turned on these axes toward any part of the sky. It is a heavy instrument, but so perfectly balanced that the astronomer moves it easily with one hand.
The principle transit circle was a 3-inch Combined Transit and Zenith telescope designed by Warner & Swasey especially for Illinois. The objective, by John Brashear, was held in place by a special cell that compensated for the different temperature conductivities of the brass and glass so that temperature had no effect on the location or separation of the lenses. Designated as model M-505, the transit included a handing level, micrometer and a built in reversing mechanism. This transit was located in the east-central transit room allowing direct access to the clock room through a small window. The instrument cost $1200 in 1896.
The transit circle was capable of determining both right ascension and declination of a star, unlike the more simple and common transit instrument that can only determine the right ascension. Such an instrument could also be used to set the Observatory’s clocks by observing standard stars whose position was precisely known.
In addition there were three other smaller transit telescopes, a sidereal clock by Riefler, and other accessories including sextants, chronometers, and teaching tools.
Historic significance
The observatory holds significance in astronomy because of its association with the development of seleniumSelenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
photoelectric cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
. The cell revolutionized the science of astronomical photoelectric
Photoelectric effect
In the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as photoelectrons...
photometry
Photometry (astronomy)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation...
. This branch of astronomy measures stellar magnitude. The research regarding photometry was conducted on a 12 inches (304.8 mm) Warner and Swasey
Warner & Swasey Company
The Warner & Swasey Company was an American manufacturer of machine tools, instruments, and special machinery. It operated as an independent business firm, based in Cleveland, from its founding in 1880 until its acquisition in 1980...
refractor telescope in the second-story equatorial room. The selenium cell was developed by Joel Stebbins
Joel Stebbins
Joel Stebbins was an American astronomer who pioneered photoelectric photometry in astronomy. He earned his Ph.D at the University of California. He was director of the University of Illinois Observatory from 1903 to 1922 where he performed innovative work with the selenium cell...
from 1907 to 1922 while he directed the observatory. As a result of Stebbins' work determining stellar magnitude using photoelectric photometry, it became standard technique. Due to this astronomical importance the observatory was listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
on November 6, 1986 and on December 20, 1989 the U.S. Department of Interior designated the U of I Observatory a National Historic Landmark
National Historic Landmark
A National Historic Landmark is a building, site, structure, object, or district, that is officially recognized by the United States government for its historical significance...
.
Further reading
- Baker, Robert, H. "Telescope and photometer of the University of Illinois Observatory," Popular Astronomy, Vol. 36, p. 86, Jan. 1928.
- Francissen, Shauna J. "National Register of Historic Places Inventory-Nomination Form-University of Illinois Astronomical Observatory.", (PDF), Urbana, Illinois: Preservation and Conservation Association, 1986.
- Myers, G.W. "The Astronomical Observatory at the University of Illinois." Popular Astronomy, 6 (1898).
- Stebbins, Joel, and F.C. Brown. Determination of the Moon's Light with a Selenium Photometer,'" Astronomical Journal, December 1907.
- Stebbins, Joel. "Early Photometry at Illinois" Publications of the Astronomical Society of the Pacific, December 1957.
- Stebbins, Joel. "The Electric Photometry of Stars," Publications of the Astronomical Society of the Pacific, Vol. 52, No. 308, p.235, 1940.
- Stebbins, Joel. "Jacob Kunz, 1874-1938," Popular Astronomy, March 1939.
- Stebbins, Joel. The Brightness of Halley's Comet as Measured With a Selenium Photometer," Astrophysical Journal, July 1910.
- Stebbins, Joel. "The Washburn Observatory," Publications of the Astronomical Society of the Pacific, Vol. 70, No. 416, p.437, 1958.
- Struve, Otto, and Velta Zebergs. Astronomy of the Twentieth Century. New York: Macmillan, 1962.
- Svec, Michael T. "The birth of electronic astronomy," Sky and Telescope, May 1992.
- Tenn, Joseph S. "The Rise and Fall of Astrophotography," Griffith Observer, 53, 8, 2 Aug. 1989.
- University of Illinois Archives, Observatory file, Urbana, Illinois.
- Warner and Swasey. A Few Astronomical Instruments. Cleveland, 1900.
- Whitford, A.E. '"American Pioneer in Photoelectric Photometry,"' Sky and Telescope, May 1966.