Citizen Scientist Wins Prestigious AAS Award

By: Diana Hannikainen January 25, 2024 1

The American Astronomical Society recognized Dan Caselden’s contributions to science at their recent winter meeting.

Since the mid-2000s, the American Astronomical Society (AAS) has been recognizing citizen scientists and amateur astronomers who have contributed significantly to advances in astronomical research with its Chambliss Amateur Achievement Award. Past recipients have worked in fields ranging from wide-field imaging to exoplanet studies to the theory of high-energy phenomena.

Earlier this year, at its 243rd meeting held in January in New Orleans, Louisiana, the AAS conferred the Chambliss Award to Dan Caselden for his "outstanding participation in the Backyard Worlds citizen science projects, including pioneering the application of machine learning to solar neighborhood ultracool dwarf searches."

a blue orb with a red ring at its top on a black background — This artist concept portrays the brown dwarf W1935, one of citizen scientist Dan Caselden's discoveries. Astronomers using NASA’s James Webb Space Telescope found methane emission coming from W1935. This indication of aurora is unexpected because the brown dwarf is cold and lacks a host star.
*NASA / ESA / CSA / L. Hustak (STScI)*

Like previous recipients, Caselden is not a professional astronomer — he’s a computer security researcher. But in 2017, he was looking for a more satisfying pastime while exercising on his bike than playing video games or watching TV. That’s when he stumbled upon Backyard Worlds: Planet 9, a NASA-led citizen-science project dedicated to searching for new brown dwarfs near the Sun, as well as the (thus far) elusive Planet 9.

“Backyard Worlds drew me in with a needle-in-a-haystack challenge to find missing objects in and near our solar system,” Caselden writes in an email. And the rest, as they say, is history.

The citizen scientists who participate in the Backyard Worlds project comb through reams of data from NASA’s Wide-field Infrared Survey Explorer (WISE) in the quest for extremely dim brown dwarfs. These worlds are tough to find. And this is where Caselden steps in: Along with his colleague Paul Westin, he built an interactive browser tool that could efficiently visualize WISE images. The adoption of WiseView, as he named this tool, precipitated the rise in the rate of discovery of brown dwarfs — citizen scientists and researchers alike started finding them in dizzying numbers.

Caselden himself has unveiled a number of objects using WiseView, including several weird brown dwarfs. For example, WISE J0830+2837 (discovered with fellow citizen scientist Guillaume Colin) is one of the coldest brown dwarfs found to date. Astronomers categorize brown dwarfs, based on their infrared spectra, into spectral types L, T, and Y (an extension of the familiar OBAFGKM spectral classification). Brown dwarfs don’t shine with their own light, instead glowing with the warmth from their formation. Y, being the coolest, is also the faintest type of brown dwarfs, and most challenging to detect. These brown dwarfs typically have temperatures below 350°F or so. In addition to finding the Y-dwarf WISE J0830, Caselden also found WISE J1534-1043, nicknamed “The Accident.” It’s truly bizarre, for it might be a type-Y subdwarf, an entirely new class of object.

Also at the 243rd AAS meeting, Caselden’s colleague Jackie Faherty (senior scientist at the American Museum of Natural History’s Department of Astrophysics and cofounder of the Backyard Worlds project) announced at a press conference the detection of aurorae on WISE J1935-1546, another brown dwarf Caselden discovered.

Dan Caselden visiting the BDNYC group at the AMNH — Caselden is based in Massachusetts but visits the American Museum of Natural History when he can. Here he is with his colleagues of the Brown Dwarfs in New York City team. Back row, left-to-right: Niall Whiteford, Mohammad Alvi Refat, Everett D McArthur, Mark Popinchalk, Jasmine Ramirez, Johanna Vos, Andrew Ayala, Azul Ruiz Diaz, Kelle Cruz. Front row, left-to-right: Dan Caselden, Austin Rothermich, Genaro Suárez, Rosario Cecilio-Flores-Elie, Jackie Faherty, Sherelyn Alejandro, Jolie L'Heureux.
*Jackie Faherty*

Caselden is a prolific researcher — his contributions to citizen science don’t stop at Backyard Worlds. The various “extracurricular” activities and projects he’s involved in include the CatWISE astronomical catalog (that collates more than 10 years of WISE images, led by Caltech), as well as serving as co-investigator on NOIRLab’s recently launched Backyard Worlds: Cool Neighbors.

Dan Caselden and family at the AMNH — Caselden also has some fun while doing his important work at the AMNH. Here he is with his mother and daughter in front of one of the amethyst geodes in the museum's Mignone Halls of Gems and Minerals.
*Dan Caselden*

Caselden relishes the cross-discipline collaborative effort involved in this work: “With extensive mentorship by the science team and fellow security researchers,” he says, “we built visualization and machine learning systems to vastly expand the body of known nearby brown dwarfs and pick up a few weirdos like ‘The Accident’ along the way.”

To underline the fruit of his hard work, Caselden is currently a coauthor on 25 peer-reviewed publications . . . and counting. We can’t wait to see where his ongoing efforts will take him. Keep up the good work, Dan!

Do you know someone who contributes to professional astronomical research, like Caselden does, either in the capacity of a citizen scientist or within the framework of a pro-am collaborative project? If yes, keep an eye on the Chambliss Amateur Achievement Award webpage to see when the next round for nominations opens up — you can nominate your friend . . . or even yourself (self-nominations are allowed!).