Next-Gen Astronomical Survey Makes Its First Observations Toward a New Understanding of the Cosmos

The Sloan Digital Sky Survey’s 2.5-meter telescope in New Mexico. SDSS Team, Fermilab Visual Media Services

The Sloan Digital Sky Survey’s fifth generation (SDSS-V) collected its very first observations of the cosmos at 1:47 a.m. on October 24, 2020. As the world’s first all-sky time-domain spectroscopic survey, SDSS-V will provide groundbreaking insight into the formation and evolution of galaxies — including our own Milky Way — and of the supermassive black holes that lurk at their centers.

The newly launched SDSS-V will continue the path-breaking tradition set by the survey’s previous generations, with a focus on the ever-changing night sky and the physical processes that drive these changes, from flickers and flares of supermassive black holes to the back-and-forth shifts of stars being orbited by distant worlds. SDSS-V will provide the spectroscopic backbone needed to achieve the full science potential of satellites like NASA’s TESS, the European Space Agency’s Gaia and the latest all-sky X-ray mission, eROSITA.

“My personal interest in SDSS-V is that it is going to produce the most precise and complete map of the Milky Way ever made,” says David W. Hogg, leader of the Astronomical Data group at the Flatiron Institute’s Center for Computational Astrophysics (CCA) in New York City. “The map SDSS-V makes of the Milky Way is not just of where the stars are; it is also of how those stars are moving, and what those stars are made of. This information tells us about the past and future of the galaxy.”

Hogg and his CCA colleagues are among those looking forward to diving into the new data. The CCA, along with Columbia University and New York University, together make up the SDSS-V’s Gotham Participation Group. The group participates in the design, execution and scientific exploitation of the survey. Previous generations of the Sloan Digital Sky Survey produced powerful insights for astronomers, and this next generation will do the same, predicts Kathryn Johnston, leader of the CCA’s Dynamics group and a Columbia professor.

“SDSS was the pioneering data set that launched the field of near-field cosmology, allowing us to discuss the implications of discoveries about our home galaxy for galaxies across the universe,” Johnston says. “I am excited to be joining in the next venture.”

As an international consortium, SDSS has always relied heavily on phone and digital communication. But adapting to exclusively virtual communication tactics was a challenge, along with tracking global supply chains and laboratory availability at various university partners as they shifted in and out of lockdown during the final ramp-up to the survey’s start. Particularly inspiring were the project’s expert observing staff, who worked in even greater than usual isolation to shut down, and then reopen, the survey’s mountaintop observatories.

“In a year when humanity has been challenged across the globe, I am so proud of the worldwide SDSS team for demonstrating — every day — the very best of human creativity, ingenuity, improvisation and resilience. It has been a challenging period for SDSS and the world, but I’m happy to report that the pandemic may have slowed us, but it has not stopped us,” says SDSS-V Director Juna Kollmeier, of the Carnegie Institution for Science.

The collaborative nature of the SDSS is particularly important, says Melissa Ness, an assistant professor at Columbia and an associate research scientist at the CCA. “Beyond being a truly breathtaking scientific endeavor, being part of Sloan-V means working with and learning from a group of dedicated scientists who are working openly and collaboratively to deliver the data that will enable us to answer fundamental questions about our galactic origins,” she says. “I am thrilled that I am working in this field at this time, and am looking forward to the coming years within galactic archaeology.”

Funded primarily by member institutions, along with grants from the Alfred P. Sloan Foundation, the U.S. National Science Foundation, and the Heising-Simons Foundation, SDSS-V will focus on three primary areas of investigation, each exploring different aspects of the cosmos using different spectroscopic tools. Together these three project pillars, called “Mappers,” will observe more than six million objects in the sky, and monitor changes in more than a million of those objects over time.

The survey’s Local Volume Mapper will enhance our understanding of galaxy formation and evolution by probing the interactions between the stars that make up galaxies and the interstellar gas and dust that is dispersed between them. The Milky Way Mapper will reveal the physics of stars in our Milky Way, the diverse architectures of its star and planetary systems, and the chemical enrichment of our galaxy since the early universe. The Black Hole Mapper will measure masses and growth, over cosmic time, of the supermassive black holes that reside in the hearts of galaxies, and of the smaller black holes left behind when stars die.

“We are thrilled to start taking the first data for two of our three Mappers,” adds SDSS-V spokeswoman Gail Zasowski, of the University of Utah. “These early observations are already important for a wide range of science goals. Even these first targets provide data for studies ranging from mapping the inner regions of supermassive black holes and searching for exotic multiple–black hole systems, to studying nearby stars and their dead cores, to tracing the chemistry of potential planet-hosting stars across the Milky Way.”

“SDSS-V will continue to transform astronomy by building on a 20-year legacy of path-breaking science, shedding light on the most fundamental questions about the origins and nature of the universe. It demonstrates all the hallmark characteristics that have made SDSS so successful in the past: open sharing of data, inclusion of diverse scientists and collaboration across numerous institutions,” says Evan Michelson, program director at the Sloan Foundation. “We are so pleased to support Juna Kollmeier and the entire SDSS team, and we are excited for this next phase of discovery.”

SDSS-V will operate out of both Apache Point Observatory in New Mexico, home of the survey’s original 2.5-meter telescope, and Carnegie’s Las Campanas Observatory in Chile, where it uses the 2.5-meter du Pont telescope.

SDSS-V’s first observations were taken in New Mexico with existing SDSS instruments, in a necessary change of plans due to the pandemic. As laboratories and workshops around the world navigate safe reopening, SDSS-V’s own suite of new innovative hardware is on the horizon — in particular, systems of automated robots to aim the fiber optic cables used to collect the light from the night sky. These robots will be installed at both observatories over the next year. New spectrographs and telescopes are also being constructed to enable the Local Volume Mapper observations.

For more information, please see the SDSS-V’s website at

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