On Feb. 24, astronomers’ computers around the world lit up with a deluge of cosmic notifications — 800,000 alerts about new asteroids in our solar system, exploding stars across the galaxy and other noteworthy changes in the night sky. The discoveries were made by the Simonyi Survey Telescope at the NSF-DOE Vera C. Rubin Observatory in Chile and distributed globally within about two minutes.
That flurry of notifications marked the commencement of the observatory’s Alert Production Pipeline, a sophisticated software system developed at the University of Washington that is eventually expected to produce up to seven million alerts per night.
“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,” said Eric Bellm, a research associate professor of astronomy at the UW who leads the Alert Production Pipeline Group for the Rubin Observatory. “Rubin will survey the sky at an unprecedented scale and allow us to find the most rare and unusual objects in the universe. We can’t wait to see the exciting science that comes from these data.”
The beginning of scientific alerts is one of the last major milestones before Rubin Observatory launches its Legacy Survey of Space and Time (LSST) later this year. During the LSST, Rubin will scan the Southern Hemisphere sky nightly for 10 years to precisely capture every visible change using the largest digital camera ever built. These alerts will chronicle the treasure trove of scientific discoveries that Rubin will make through its time-lapse record of the universe. In the first year of the LSST, Rubin is expected to capture images of more objects than all other optical observatories combined in human history.
The UW played a central role in the software that enabled this month’s milestone. The alert pipeline was developed by a team of about two dozen researchers and software developers in the astronomy department’s Institute for Data Intensive Research in Astrophysics & Cosmology (DiRAC). The team has spent the past decade working with other data management teams around the country to figure out how to process the staggering 10 terabytes of images that Rubin produces every night, and will continue to develop and operate the alert system throughout the 10-year LSST survey.
“Enabling real-time discovery on such a massive data stream has required years of technical innovation in image processing algorithms, databases and data orchestration. We’re thrilled to continue the UW’s legacy of excellence in data-driven science.” Bellm said.
While the night sky seems calm and unchanging to the casual viewer, it’s actually alive with motion and transformation. Each alert signals something that has changed in the sky since Rubin last looked — a new source of light, a star that brightened or dimmed, or an object that moved. With Rubin’s alerts, scientists will have a greater ability to catch supernovae in their earliest moments, discover and track asteroids to assess potential threats to Earth and spot rare interstellar objects as they race through the solar system.
Scientists can use these data to better understand the nature of dark matter, dark energy and other unknown aspects of the universe.
“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,” said Kathy Turner, program manager in the High Energy Physics program in the U.S. Department of Energy’s Office of Science. “Rubin Observatory’s groundbreaking capabilities are revealing untold astrophysical treasures and expanding scientists’ access to the ever-changing cosmos.”
Every 40 seconds during nighttime observations, Rubin captures a new region of the sky. It then sends the data on a seconds-long journey from Chile to the U.S. Data Facility (USDF) at the SLAC National Accelerator Laboratory in California for initial processing. Rubin’s data management system automatically compares it to a template made from previous images of the same region. This comparison allows it to detect the slightest variations. With every change, such as the appearance of a new point of light, an object’s movement or a change in brightness, the system generates a public alert within two minutes.
“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. Go.’”
Rubin’s alerts are public, meaning anyone — from professional researchers to students and citizen scientists — can access and explore them. The speed of the alerts allows scientists using other ground- and space-based telescopes around the world to coordinate follow-up observations. This collaboration will enable fast and detailed studies of unfolding phenomena.
Additionally, through collaborations with platforms like Zooniverse, Rubin will empower the global community to help classify cosmic events and contribute directly to discovery.
Rubin Observatory is jointly operated by NSF NOIRLab and SLAC.
For more information, contact Bellm at ecbellm@uw.edu.
This story was adapted from a press release by NOIRLab and SLAC.
Operations of the Vera C. Rubin Observatory are funded by the U.S. National Science Foundation and the U.S. Department of Energy’s Office of Science.