The Allegheny Observatory: Stargazing in Pittsburgh
Perched atop a scenic hill within Riverview Park, the Allegheny Observatory is a distinguished astronomical research institution. It’s a part of the Physics and Astronomy Department at the University of Pittsburgh, and it has been contributing significantly to the field of astrometry since 1859.
History and Establishment
The idea for the Allegheny Observatory was sparked in 1859 by a group of three astronomy enthusiasts from Allegheny City, who collaborated with 29 others to establish the “Allegheny Telescope Association.” The observatory was officially established on February 15, 1859, and was originally intended as a public education institution rather than a research facility.
By 1867, however, the focus had shifted to research, and the observatory was donated to the Western University of Pennsylvania, now known as the University of Pittsburgh. The university appointed Samuel Pierpont Langley as the first director. Under his leadership, a research program into sunspots was initiated, and Langley’s detailed drawings of sunspots continue to be used in astronomical textbooks.
Architectural Marvel
The observatory building we see today was not the original structure. In 1900, the cornerstone of a new observatory was laid a few miles away from the city, within the current Riverview Park. This impressive hilltop edifice, adorned in Classic Revival style, was designed by Thorsten E. Billquist and completed in 1912. The tan brick and white terra cotta structure symbolize the unity of art and science.
This L-shaped building houses a library, lecture hall, classrooms, laboratories, offices, and three hemispherical domed telescope enclosures. Two of these domes were dedicated to research, while one was reserved for use by schools and the general public. The core of the building is a small rotunda, housing an opalescent glass window depicting Urania, the Greek muse of astronomy, designed by artist Mary Elizabeth Tillinghast.
The original observatory building was converted into an athletics training facility in 1907 and was eventually sold to the Protestant Orphan Asylum. It was demolished in the 1950s, and the site is now occupied by Triangle Tech.
Telescopes and Research
The Allegheny Observatory is home to three main telescopes: the Thaw Memorial Refractor, the Keeler Memorial Reflector, and the Fitz-Clark Refractor. The Thaw Memorial Refractor, a 30-inch refracting telescope, is one of the largest in the world and has created more than 110,000 glass plate exposures over the past 110 years. It continues to observe the stars every clear night, primarily searching for new planets around distant stars.
The Keeler Memorial Reflector, a 24-inch PlaneWave CDK, has been replaced by an automated 16-inch Meade telescope. The Fitz-Clark Refractor, a 13-inch refracting telescope, is often used for public viewing during tours and observing sessions.
The Birth of Standard Time
One of the most notable contributions of the Allegheny Observatory to the world was the creation of the first standardized time, known as “Allegheny Time”. This system, initiated by Samuel Langley in 1869, used astronomical measurements taken at the observatory to accurately determine time. The observatory would then transmit a telegraph signal at exactly noon each day, which was adopted by railroad stations across the country to set their clocks. This service eventually extended over 2,500 miles, reaching 300 telegraph offices.
On November 18, 1883, the Allegheny Observatory transmitted a signal marking noon, Eastern Standard Time. Railroads across North America synchronized their schedules based on this signal, marking the first day of railroad standard time. The standard time system that began on this day continues in North American use to this day.
Current Work and Future Plans
Today, the main active research pursuit at the Allegheny Observatory involves detecting extrasolar planets. This is done using photometry, a practice of measuring the brightness of stars. If a planet crosses (or transits) in front of its parent star’s disk, the observed visual brightness of the star drops a small amount, indicating the presence of the planet. The research team comprises students from the University of Pittsburgh, whose observations have recently contributed to observing a transit of the planet HD 80606 b.
In addition to research, the observatory also offers public tours, free of charge, a couple of nights each week. These tours include a short slide or film presentation, a walking tour of the building, and an opportunity to observe celestial objects through the Fitz-Clark Refractor.
A Stargazing Haven
While Pittsburgh may not be the first place that comes to mind when thinking of stargazing destinations, the Allegheny Observatory offers a unique opportunity to explore the cosmos without leaving the city. Its rich history, ongoing research, and commitment to public education make it a significant landmark in the world of astronomy.
Whether you’re an astronomy enthusiast or a casual stargazer, the Allegheny Observatory offers a captivating experience. Its doors are open to the public, allowing everyone a chance to touch the stars and learn more about our universe. Its continued service to the community and contribution to science make it a true gem in Pittsburgh.
