Donald G. York honored for ‘exceptional vision’ in helping to found the Sloan Digital Sky Survey

Eminent UChicago astronomer to receive 2022 George Van Biesbroeck Prize from the American Astronomical Society

When Donald York was a student beginning his career in astronomy in the 1960s, it was very difficult to get enough time on a telescope to make observations.

“We were suffering from a deficit of data,” said York, the University of Chicago Horace B. Horton Professor Emeritus in the Department of Astronomy and Astrophysics and the Enrico Fermi Institute.

What he envisioned instead was a comprehensive map of the universe.

More than half a century later, the American Astronomical Society has announced that it will present its 2022 George Van Biesbroeck Prize to York for his work to found and design the Sloan Digital Sky Survey.

The Sloan Digital Sky Survey was the first very large telescope survey. It revolutionized access to data and built a tool for the professional astronomer and novice alike to explore a vast portion of the sky from their desktop. The American Astronomical Society calls it "one of the most important and transformational facilities in astronomy.”

The George Van Biesbroeck Prize is presented biannually and honors a living individual for long-term extraordinary or unselfish service to astronomy. The award cited York “for exceptional vision in the conception and design of the Sloan Digital Sky Survey, a major imaging and spectroscopic survey that has created the most detailed three-dimensional maps of the universe ever made." 

“As the prime mover of the Astrophysical Research Consortium’s Apache Point Observatory in southern New Mexico, including its 3.5-meter, multi-purpose telescope and the dedicated Sloan Digital Sky Survey project—one of the most scientifically productive projects in astronomy—Don York has been a pioneering leader of modern optical astronomy and rebuilt the University of Chicago’s leadership in this field,” said Prof. Joshua A. Frieman, a UChicago astrophysicist and former head of the Particle Physics Division at Fermi National Accelerator Laboratory.

A democratization of astronomy

Before the Sky Survey, gaining access to a telescope to make observations and document objects of study was heavily limited by resources. 

“You could only get about six nights a year for your own personal work on a telescope,” said York, who began his career in 1966 as a student at the University of Chicago's Department of Astronomy and Astrophysics. “You might find a group to contribute to the data pool for a project and document a small sample, but you were limited by who could work together, how much time people could spend, and how much perfection could be demanded.”

These small groups worked on different telescopes to get similar data, which made data quality standardization very difficult. York knew if the observations came from one telescope it would dramatically improve reliability.

With enough eyes, they could document “millions and millions of objects and their characterizations” in a portion of the sky, opening up possibilities unimaginable to the individual observer. A large collaborative survey could also reinvent how data was collected, published, and shared. 

To set about doing this, York—along with UChicago Prof. Emeritus Richard Kron and Princeton University astronomer James Gunn—began to plan a very large survey using a next generation telescope that could observe faint objects and attain statistical measurements of the way galaxies clustered on large scales. 

In 1988, they wrote down the names of people they thought could join them in the effort. York recalled about 20 people met at two meetings at the airport, now known as the O’Hare meetings. They documented the principles, telescope characteristics, and funding strategies they would pursue.

Any group who joined would be eligible for two-year access to the data. After two years, the data would be released to the public and distributed free to all online, which was revolutionary. Compared to the major institutional investments usually required to join, the cost would be very low. No one could claim possession of the data and it would be available to everybody. 

An advantage would be unified and elevated standards for data to qualify for inclusion—an endeavor York was proud to lead. “The data needed to be the very best that we could measure such that all agreed to the highest standards for data reduction and quality,” he said. “And everybody took that very seriously.”

Prof. Emeritus Stuart Rice—the former dean of the Physical Sciences Division—and Jerry Ostriker, PhD’64, then the chair of Princeton’s Department of Astrophysical Sciences, were brought onto the Board. Fermilab would join in 1990 to provide an experimental group. The National Science Foundation contributed support for the telescope build. Kron mainly did the organizing and Gunn specified the technology and project design.

The technology they would need—a camera using many charge-coupled devices (CCDs) that was 100 times more efficient than photographic plates—had recently become feasible to build, and they already had a site in mind for the telescope at a newly-built observatory at Apache Point, New Mexico.

They first built a 3.5-meter telescope for remote observing with five universities. Then with input from several designers and funding from the NSF and the Sloan Consortium of 30 members, they applied what they had learned to build a smaller 2.5-meter telescope, now called the Sloan Foundation Telescope.

The Sloan Digital Sky Survey's camera took its first images in 1998, with the official survey beginning in 2000—over a decade after the initial O'Hare meetings. York served as the first director, and Kron was the third, finishing out part I of the survey and remaining in the role until part II was completed in 2008. 

Now anticipating their fifth phase (SDSS-V) in 25 years, the Sloan Digital Sky Survey has created the most detailed three-dimensional maps of the universe and recorded the spectra—light spread out across its component wavelengths—for more than three million astronomical objects.

The Sloan Digital Sky Survey data is the foundation of hundreds of studies, and its public data sets are still being used in countless research projects. It also set a precedent that has been followed ever since by major collaborations.

“Don strongly supported the idea that the Sloan Digital Sky Survey should make its data freely available, highly accessible, science-ready, and well documented,” said Kron. 

“This vision was duly achieved, and resulted in a democratization of astronomy in the sense that the volume and quality of Sloan Digital Sky Survey data enable anyone to undertake research projects, without needing access to specialized facilities,” he said. “The Sloan Digital Sky Survey became, and still is, a model for other projects regarding public distribution of astronomical data. This is an amazing achievement and has helped the scientific careers of so many people.”

Prof. John Carlstrom, chair of the Department of Astronomy and Astrophysics, leads the South Pole Telescope and is among the astronomical survey architects who have benefitted from Sloan’s example of success.

"Don York is an inspiration to all of us,” Carlstrom said. “He is an extraordinary astrophysicist whose insatiable curiosity has led him to make enormous contributions to our understanding of the workings of the universe, from insights into the mysterious features seen in the diffuse gas between the stars to the evolution of the entire universe. His leadership in the Sloan Digital Sky Survey led to what is arguably the most impactful observatory ever built.”

The award will be presented at a ceremony in Seattle in 2023.

—Adapted from a story first published by the Physical Sciences Division. For more information on this prize, visit the American Astronomical Society website.