One of the newest astronomical observatories on Earth is expected to produce up to seven million alerts of asteroids, glowing black holes and cosmic explosions every night.
It's already come up with 800,000 alerts during its first night tracking the sky.
The NSF–DOE Vera C. Rubin Observatory is located in northern Chile and boasts the biggest digital camera on Earth.
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It released its first alerts documenting events in the night sky in late February 2026, and astronomers expect it will eventually produce up to seven million alerts a night.
Astronomers say this is the beginning of a new era of real-time observation of the night sky over Earth.
Rubin's alerts to real-time cosmic events
The Vera C. Rubin Observatory issued 800,000 alerts to astronomers on a single night on 24 February 2026.
These alerts drew astronomers' attention to new asteroids, exploding stars (known as supernovae), active galactic nuclei (glowing supermassive black holes at the centres of galaxies) and variable stars whose brightnesses change over time.
Astronomers say the beginning of scientific alerts is one of the final milestones before the Rubin Observatory begins its Legacy Survey of Space and Time.
The LSST will see Rubin will scan the Southern Hemisphere sky every night for a decade looking for visible changes in the sky.
This will provide a time-lapse record of our changing Universe and is expected to lead to a wealth of discoveries.
In the first year of the LSST, Rubin is predicted to capture images of more objects than all other optical observatories combined throughout human history.
A record of the changing Universe
"By connecting scientists to a vast and continuous stream of information, NSF–DOE Rubin Observatory will make it possible to follow the Universe’s events as they unfold, from the explosive to the most faint and fleeting," says Luca Rizzi, a program director for research infrastructure at NSF.
"The discoveries reported in these alerts reflect the power of NSF–DOE Rubin Observatory as a tool for astrophysics and the importance of sustained federal support," says Kathy Turner, program manager in the High Energy Physics program in the DOE’s Office of Science.
"Rubin Observatory’s groundbreaking capabilities are revealing untold astrophysical treasures and expanding scientists’ access to the ever-changing cosmos."
When powerful telescopes like Rubin are pointed at the sky, they reveal that the cosmos is constantly changing and transforming in dramatic, chaotic ways.
Rubin's alerts reveal new sources of light, stars changing brightness and objects moving.
Scientists say Rubin will give them more opportunity to catch supernovae before they reach their peak and find asteroids that could be a threat to Earth.
They could also help spot many more interstellar comets like 3I/ATLAS as they pass through our Solar System.
Scientists can then use other telescopes to conduct follow-up observations.
"Rubin's alert system was designed to allow anyone to identify interesting astronomical events with enough notice to rapidly obtain time-critical follow-up observations," says Eric Bellm, Alert Production Pipeline Group Lead for Rubin Data Management from NSF NOIRLab and the University of Washington.
"Enabling real-time discovery on 10 terabytes of images nightly has required years of technical innovation in image processing algorithms, databases, and data orchestration. We can’t wait to see the exciting science that comes from these data."
How Rubin tracks the changing sky
The Rubin Observatory compares each image it captures with a template image, built by combining previous images of the same area. This reveals how the image has changed over time.
Any changes trigger an alert to astronomers and could reveal supernovae, variable stars, active galactic nuclei and Solar System objects.
Rubin captures a new region of the sky every 40 seconds, then sends that data to a facility in California, USA for processing.
The automated system compares it to a template made from previous images of the same region.
"The scale and speed of the alerts are unprecedented," says Hsin-Fang Chiang, a SLAC software developer leading operations for data processing at the USDF.
"After generating hundreds of thousands of test alerts in the last few months, we are now able to say, within minutes, with each image, 'here is everything' and 'go.'"
Rubin is expected to produce so many alerts, scientists will rely on a network of intelligent software platforms called brokers that use machine learning.
"The extraordinary number of alerts that Rubin will produce presents an exciting challenge for both astronomers and software engineers," says Tom Matheson, Interim Director of the Community Science and Data Center (CSDC).
"The broker teams have built systems that operate rapidly at scale so that scientists can find all of the objects of interest to them, as well as things we’ve never seen before."
"What’s revolutionary about Rubin is its ability to capture both rapid changes and long-term evolution in the sky," says Rosaria Bonito, researcher at the Italian National Institute for Astrophysics (INAF) in Palermo, Italy, and co-chair of the Rubin LSST Transients and Variable Stars (TVS) science collaboration.
"Young stars, for example, are highly dynamic and can experience sudden bursts of brightness caused by infalling matter. These events are often short-lived, and scientists can easily miss them without continuous monitoring. Rubin will allow us to detect these changes as they happen right there, right now, and also to track the evolution of stars over a decade."
