For Scientists

From historic telescopes and astronomical archives to modern instrumentation and research initiatives, Yerkes provides unique opportunities for scientists to pursue discovery, collaboration, and innovation.

Sharon & Charles Angell 40-Inch Historic Refractor

The Yerkes 40-inch refractor, completed in 1897, was the largest telescope in the world when it was built and remains the world’s largest refracting telescope.

This telescope is fully operational and is used for public observation sessions, as well as for astrophotography seminars with our summer research internships.

The refractor was the first major telescope constructed by visionary astronomer George Ellery Hale who conceived and built the world’s largest telescope four times in succession.

24-Inch Reflecting Telescope

The Yerkes 24-inch (0.6m) reflector, completed in 1967, is a research grade f/13.5 Cassegrain telescope (Boller & Chivens) with modern CCD detector and photometric filter set. It is capable of fully remote operation.

41-Inch Reflecting Telescope

The Yerkes 41-inch* (1m) reflector, completed in 1967, is a research grade f/8 Ritchey Crétien telescope (Warner & Swasey) with a modern CMOS detector and photometric filter set. It is capable of fully remote operation.

This telescope also has the option to install a Coudé mirror, which can direct starlight down an evacuated tube to the optics lab located three stories below. Two additional cable pathways (both 4” diameter) enable installation of data cables or fiber optic bundles to transport starlight to the optics lab.

*The primary mirror of this telescope measures 40 inches, but as soon as it was built, astronomers at Yerkes referred to it as “the 41-inch” telescope so as not to confuse it with the historic 40-inch refractor telescope.

Glass Plate Collection

Yerkes Observatory houses roughly 180,000 individual astronomical images and spectra captured on photographic glass plates. These plates range in size from 1-inch² up to 40-inch² and were taken between 1889 and 2002.

The photographic plates produced and studied at Yerkes in the first half of the 20th century marked the beginning of modern astrophysics, where data was captured in a way that could be measured quantitatively, published, shared, and recreated. The plates remain a valuable resource for time-domain studies because they provide a long historical record of astronomical observations. They also offer opportunities to identify unexpected phenomena that the original observers may not have recognized at the time.

Creating a publicly available, searchable database of digitized plate observations is an ongoing project at Yerkes. Various audiences can find value in exploring the plate archive, from scientists, historians, and archivists, to artists, educators, and the general public. The plates are beautiful and fascinating, they connect us to the past in a tangible way, and they provide deep potential for modern scientific discovery.

While there are challenges in both the preservation and accessibility of the plates to the audiences identified above, we are committed to maximizing the science potential and public interest of our historic collection.

Instrumentation Labs

An active area of research at Yerkes works to develop low-cost spectrographs, carrying forward the legacy of innovation into the modern state of astronomy technology development.

This project develops scientific spectrographs using off-the-shelf optics and engineer-grade 3D printed materials—all designed and constructed here at Yerkes.

These instruments can be built and used by small observatories, institutions, and even amateur astronomy communities. They can also be replicated at scale to support large spectroscopic surveys, making it possible to capture spectra from up to 10,000 astronomical objects simultaneously in a fast and cost-effective way.

The 3D Printing Lab helps more than just research. We use it to repair historic telescopes, create teaching tools, and even design custom parts for maintenance around the observatory.

Historic Collections

Yerkes is home to numerous historical astronomical instruments — some complete, some repurposed, and some in pieces — covering more than 100 years of instrument development.

Yerkes also houses more than 180,000 glass plates, recording more than 100 years of astronomical observations between the 1890s and 1990s.

The collections also include a wide variety of other historic objects, from textbooks and manuscripts to artworks and photographs.

Physical Coordinates

Latitude: 42.5704° N
Longitude: 88.5563° W
Elevation: 1057 ft (322 m)

Collaborate With Us

If you’re interested in research at Yerkes, we’d love to hear from you. For more information, fill out our contact form and we’ll be in touch.