![]() The observatory in 2013 | |||||||||||||||||||||||||||||||||||||||||||
Organization | University of Pittsburgh | ||||||||||||||||||||||||||||||||||||||||||
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Observatory code | 778 ![]() | ||||||||||||||||||||||||||||||||||||||||||
Location | Pittsburgh, Pennsylvania | ||||||||||||||||||||||||||||||||||||||||||
Coordinates | 40°28′57″N80°01′15″W / 40.482525°N 80.020829°W | ||||||||||||||||||||||||||||||||||||||||||
Established | February 15, 1859 | ||||||||||||||||||||||||||||||||||||||||||
Website | Allegheny Observatory | ||||||||||||||||||||||||||||||||||||||||||
Telescopes | |||||||||||||||||||||||||||||||||||||||||||
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The Allegheny Observatory is an American astronomical research institution, a part of the Department of Physics and Astronomy at the University of Pittsburgh. The facility is listed on the National Register of Historic Places (ref. # 79002157, added June 22, 1979) [3] and is designated as a Pennsylvania state [4] and Pittsburgh History and Landmarks Foundation [5] historic landmark.
The observatory was founded on February 15, 1859, in the city of Allegheny, Pennsylvania (incorporated into the City of Pittsburgh in 1907) by a group of wealthy industrialists calling themselves the Allegheny Telescope Association. The observatory's initial purpose was for general public education as opposed to research, but by 1867 the revenues derived from this had receded. The facility was then donated to the Western University of Pennsylvania, today known as the University of Pittsburgh.
The University hired Samuel Pierpont Langley to be the first director. One of the research programs initiated under his leadership was of sunspots. He drew very detailed drawings of sunspots which are still used in astronomical textbooks to this day. He also had the building expanded to include dark rooms, class rooms, dormitories, and a lecture hall.
In 1869, Langley created income for observatory by selling subscription service to time that was accurately determined by astronomical measurements and transmitted over telegraphs to customers. The Pennsylvania Railroad was the most influential subscriber to the "Allegheny Time" system. The Allegheny Observatory's service is believed to have been the first regular and systematic system of time distribution to railroads and cities as well as the origin of the modern standard time system. [6] By 1870, the Allegheny Time service extended over 2,500 miles with 300 telegraph offices receiving time signals. [7] On November 18, 1883, the first day of railroad standard time in North America, the Allegheny Observatory transmitted a signal on telegraph lines operated by railroads in Canada and the United States. The signal marked noon, Eastern Standard Time, and railroads across the continent synchronized their schedules based on this signal. The standard time that began on this day continues in North American use to this day. [8]
The revenues from the sale of time signals covered Langley's salary and the bills. Allegheny Observatory continued to supply time signals until the US Naval Observatory started offering it for free in 1920.
In 1878, Langley invented the bolometer, which makes very sensitive detections of thermal radiation. He used it to measure the strong variation with wavelength of Earth’s atmospheric absorption, results used by Arrhenius in 1890 demonstrating the greenhouse effect. Langley also used it to discover new infrared atomic and molecular absorption lines and make the first accurate calculation of the solar constant. Bolometers are now essential physics instruments with applications extended to astronomy, particle physics, plasma physics, and thermal cameras.
In 1895, James Keeler (AO Director: 1891-1898) obtained spectroscopy of Saturn's rings with the 13-inch Fitz-Clark Refractor, proving that the rings were particles, not solid disks as thought since the 1650s and supporting James Clerk Maxwell's 1859 calculation which indicated that tidal forces necessitate rings composed of disconnected particles. Keeler's observations launched the detailed study of Saturn's rings, which today yield insights into less accessible disk systems.
John Brashear (Allegheny Observatory Committee Chairman: 1893-1920, Allegheny Observatory Director: 1898-1900, University of Pittsburgh Chancellor: 1901-1904) made many high-quality optics and precision instruments at his Allegheny-Observatory-affiliated shop, including the optical surfaces for the famous 1887 Michelson-Morley interferometer, which demonstrated the constant speed of light regardless of motion direction. This was a watershed moment in physics history, leading to Einstein’s theory of special relativity. Brashear also made the impressive 47-foot long 30-inch Thaw Refractor still in use at Allegheny Observatory.
In 1914, Frank Schlesinger (Allegheny Observatory Director: 1905-1920) began pioneering the use of photographic methods with the long-focus Thaw Refractor to measure stellar positions and parallaxes, providing direct determinations of stellar distances. Over 110,000 exposures on glass plates were taken with the Thaw Refractor by Schlesinger and the six directors that followed him. These plates are housed at Allegheny Observatory. This was the most successful photographic parallax telescope in the world, establishing the most-accurate distance scale for the local Universe in the early 20th century.
More recently George Gatewood began using the Allegheny Observatory to search for extrasolar planets as well as to follow up on claims of extrasolar planets, starting in 1972. [9] This is done using astrometry, which is the practice of measuring the position of stars. In addition to studying the positions of stars on the thousands of photographic plates in the vaults of the observatory, George Gatewood also designed the Multichannel Astrometric Photometer (MAP) for use with the Thaw telescope to measure the position of a target star and its close neighbors on images taken 6 months apart. This technique takes advantage of parallax. If the target star has a companion then it will wobble due to the gravitational pull of the unseen companion. The size of the companion can be measured by the size of the wobble.
MAP is no longer in use and the Thaw telescope is in the process of rewiring and upgrading.
A model of the original observatory can be found in the Miniature Railroad & Village exhibit at Carnegie Science Center in Pittsburgh and in 2012 a documentary film was released covering the observatory's history. [10]
Langley was the director when he returned home in Allegheny City on July 8, 1872, following a conference. Observatory staff advised him that the lens of the 13 inch Fitz Telescope had been taken for ransom which Langley refused to pay; an argument with the unknown lens-napper ensued without resolve. It has been speculated that Langley knew the identity of the lens-napper, his or her identity is still a mystery. The lens-napper thought that with the involvement of the newspapers investigating the incidents his identity may be discovered so told Langley he could have back the lens. No clue was given as to its location but it was eventually found in a Beaver Falls, Pennsylvania, hotel wastepaper basket. It being scratched made it useless so it was re-ground by lens maker Alvan Clark. When it was reinstalled the clarity was improved so the lens-napping benefited the observatory. In gratitude, Langley added Clark's name to the telescope. [11]
Langley also researched heavier-than-air flight behind the observatory. To study the aerodynamic behavior of different forms traveling at speeds up to 70 mph, he built a 30' spring "whirling arm" to which stuffed birds and wings he made were attached. After leaving Allegheny Observatory to become secretary of the Smithsonian in 1888, he continued his flight research, designing and flying the first, unmanned, aircraft capable of stable continuously powered flight from a houseboat on the Potomac River. His full-size manned Aerodrome was funded by the U.S. Army. Two well-publicized crashes of the Aerodrome in 1903 ended his flight research.
The original observatory building was replaced by the current structure, shown in the photograph above. It was designed in the Classic Revival style by Thorsten E. Billquist. The cornerstone was laid in 1900, and the new structure was completed in 1912. It is located four miles north of downtown Pittsburgh, Pennsylvania, at Riverview Park. The building is a tan brick and white terra cotta hilltop temple whose Classical forms and decoration symbolize the unity of art and science. The L-shaped building consists of a library, lecture hall, classrooms, laboratories, offices, and three hemispherical domed telescope enclosures. Two were reserved for research; one for use by schools and the general public.
The core of the building is a small rotunda, housing an opalescent glass window depicting the Greek muse of astronomy, Urania, [12] designed by artist Mary Elizabeth Tillinghast. [13] A crypt in the basement of the observatory holds the ashes of two eminent astronomers and former directors of the Allegheny Observatory, James Edward Keeler and John Brashear. In addition, the crypt holds the remains of Brashear's wife Phoebe and Keeler's wife Cora Matthews Keeler and son Henry Bowman Keeler. [14]
The original observatory building was converted into an athletics training facility in 1907 and used by the university's football team. [15] [16] The original observatory building was sold, along with the rest of the adjacent university buildings, to the Protestant Orphan Asylum prior to the move of the main academic portion of the university to the Oakland section of Pittsburgh in 1909. [17] The original observatory building was torn down in the 1950s and the site is now occupied by Triangle Tech.
The main active research pursuit at the Allegheny Observatory involves detections of extrasolar planets. [18] This is done using photometry, which is the practice of measuring the brightness of stars. The brightness of a target star and its close neighbors are measured on digital images taken every 30–60 seconds, and if a planet crosses (transits) in front of its parent star's disk, then the observed visual brightness of the star drops a small amount. The amount the star dims depends on the relative sizes of the star and the planet. The research team consists of students at the University of Pittsburgh whose observations have recently contributed to a collaborative effort to observe a transit of the planet HD 80606 b. [19] The group is also actively contributing to upgrading the Allegheny Observatory.
In 2009, the university's Department of Geology and Planetary Science installed Western Pennsylvania's only seismic station, which is connected to IRIS Consortium networks, in the observatory. [20]
When the new Allegheny Observatory was designed it was done with the public in mind; the floor plan included a lecture hall. When the new facility first went into operation, on every clear evening it was opened for the public to look through the 13" telescope but if it were a cloudy night "they would be given an illustrated lecture on astronomy." John Brashear once said "the Allegheny observatory would remain forever free to the people" and to this day it has [21] although in modern times the free public tours are only offered a couple nights each week.
Samuel Pierpont Langley was an American aviation pioneer, astronomer and physicist who invented the bolometer. He was the third secretary of the Smithsonian Institution and a professor of astronomy at the University of Pittsburgh, where he was the director of the Allegheny Observatory.
Yerkes Observatory is an astronomical observatory located in Williams Bay, Wisconsin, United States. The observatory was operated by the University of Chicago Department of Astronomy and Astrophysics from its founding in 1897 until 2018. Ownership was transferred to the non-profit Yerkes Future Foundation (YFF) in May 2020, which began millions of dollars of restoration and renovation of the historic building and grounds. Yerkes re-opened for public tours and programming in May 2022. The April 2024 issue of National Geographic magazine featured a story about the Observatory and ongoing work to restore it to relevance for astronomy, public science engagement and exploring big ideas through art, science, culture and landscape. The observatory offers tickets to programs and tours on its website.
The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The observatory is managed by the University of California Observatories, with headquarters on the University of California, Santa Cruz campus, where its scientific staff moved in the mid-1960s. It is named after James Lick.
A refracting 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 spyglasses and astronomical telescopes but is also used for long-focus camera lenses. Although large refracting telescopes were very popular in the second half of the 19th century, for most research purposes, the refracting telescope has been superseded by the reflecting telescope, which allows larger apertures. A refractor's magnification is calculated by dividing the focal length of the objective lens by that of the eyepiece.
James Edward Keeler was an American astronomer. He was an early observer of galaxies using photography, as well as the first to show observationally that the rings of Saturn do not rotate as a solid body.
Standard time is the synchronization of clocks within a geographical region to a single time standard, rather than a local mean time standard. Generally, standard time agrees with the local mean time at some meridian that passes through the region, often near the centre of the region. Historically, standard time was established during the 19th century to aid weather forecasting and train travel. Applied globally in the 20th century, the geographical regions became time zones. The standard time in each time zone has come to be defined as an offset from Universal Time. A further offset is applied for part of the year in regions with daylight saving time.
Frank Washington Very was a U.S. astronomer, astrophysicist, and meteorologist. He was born in Salem, Massachusetts, and educated at Massachusetts Institute of Technology (1873) where he taught physics after his graduation.
John Alfred Brashear was an American astronomer and instrument builder.
Ladd Observatory is an astronomical observatory at Brown University in Providence, Rhode Island. Founded in 1891, it was primarily designed for student instruction and research. The facility operated a regional timekeeping service. It was responsible for the care and calibration of clocks on campus including one at Carrie Tower and another that rang the class bell at University Hall. Meteorological observations were made there from the time the building opened using recording weather instruments.
The Amateur Astronomers Association of Pittsburgh (AAAP) is an Astronomical Organization founded on June 9, 1929, by Chester B. Roe and Leo J. Scanlon. Since its establishment, it has grown to have over 500 members and operates two observatories in the Pittsburgh region: the Nicholas E. Wagman Observatory and the Mingo Creek Park Observatory. The club also sponsors many star parties that are open to the public throughout the year.
Laws Observatory is the name of three separate astronomical observatories owned and operated by University of Missouri from 1880 to the present. Named after former University President Samuel Laws, it is located in Columbia, Missouri (USA).
Sproul Observatory was an astronomical observatory owned and operated by Swarthmore College. It was located in Swarthmore, Pennsylvania, United States, and named after William Cameron Sproul, the 27th Governor of Pennsylvania, who graduated from Swarthmore in 1891. The 24" telescope was moved from Sproul Observatory to Bentonville, Arkansas in July 2017.
The Theodor Jacobsen Observatory is the on-campus observatory of the University of Washington. Built in 1895, it is the second oldest building on campus and was constructed using the remaining Tenino sandstone blocks from Denny Hall, the oldest and first building on campus. The refracting telescope, enclosed within the dome, has a six-inch Brashear objective lens of a Warner & Swasey equatorial mount. The observatory also includes a transit room on the west side and a 45-seat classroom, which was built later, on the south side.
Goodsell Observatory is an observatory at Carleton College in Northfield, Minnesota, United States. It was constructed in 1887 and was, at the time, the largest observatory in the state of Minnesota, the 6th largest in the U.S., and the 12th largest in the world. The Goodsell Observatory and its predecessor, a smaller observatory that opened in 1878, served as a widely consulted timekeeping station, bringing national prominence to Carleton College in the late 19th and early 20th centuries.
Darling's Observatory, built from 1916–17, was a private observatory built by J. H. Darling in Duluth, Minnesota. The site of the observatory was on West 3rd Sreet between 9th and 10th avenues in Duluth and sat about 325 feet above Lake Superior. Plans for the building were drawn by Richard E. Schmidt of Garden & Martin of Chicago. The blueprints for the steel dome were prepared by Darling himself after inspecting domes from various other observatories. The wooden building had a stucco exterior finish.
The University of Illinois Astronomical Observatory, located at 901 S. Mathews Avenue in Urbana, Illinois, on the campus of the University of Illinois Urbana–Champaign, was built in 1896, and was designed by Charles A. Gunn. It was listed on the National Register of Historic Places on November 6, 1986, and on December 20, 1989, was designated a National Historic Landmark.
Crow Observatory is a historic observatory housed in the Crow Hall in the Physics Department on the Danforth Campus of Washington University in St. Louis. The historic telescope is still in use, and the observatory is open to the public.
Fuertes Observatory is an astronomical observatory located on the North Campus of Cornell University in Ithaca, New York. The observatory was designed by L.P. Burnham, Cornell Professor of Architecture and completed in fall of 1917. It was originally used by the Civil Engineering Department as an instructional field office for navigation and surveying. Today, the observatory is primarily used for public outreach, welcoming over two thousand visitors per year with open houses on clear Friday nights.
Nicholas E. Wagman (1905–1980) was an American astronomer and astrometrist.
Meudon Great Refractor is a double telescope with lenses, in Meudon, France. It is a twin refracting telescope built in 1891, with one visual and one photographic, on a single square-tube together on an equatorial mount, inside a dome. The Refractor was built for the Meudon Observatory, and is the largest double doublet refracting telescope in Europe, but about the same size as several telescopes in this period, when this style of telescope was popular. Other large telescopes of a similar type include the James Lick telescope (91.4), Potsdam Great Refractor (80+50 cm), and the Greenwich 28 inch refractor (71.1 cm).
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