7 million signals from space every night, global alert goes off

Every sudden flare, every moving asteroid or supernova explosion is intercepted and reported publicly within just two minutes. “Rubin’s alert system was designed to allow anyone to identify interesting astronomical events early enough to quickly obtain time-sensitive follow-up observations.”, explains Eric Bellm, head of the Alert Production Pipeline Group for NSF-DOE Rubin Observatory data management, at NSF NOIRLab and the University of Washington. “Making real-time discovery possible on 10 terabytes of images every night required years of technical innovation in image processing algorithms, databases and data orchestration. We can’t wait to see the amazing science that will come from this data”.

As new images are acquired, the Rubin Observatory’s sophisticated software automatically compares them to a pre-existing template image. The latter, created by combining Rubin’s previous shots of the same area and with the same filter, is subtracted from the newly acquired image to isolate only the changes detected. Each recorded variation triggers an automatic alert within a few minutes of shooting.

This collection shows five examples of alerts generated by Rubin related to supernovae. The images were captured during the testing phase with the LSST Camera. Each notification includes three “postage stamp” images: on the left the model image is visible, in the center the new acquisition and on the right the image obtained by subtraction, which highlights the difference and therefore the phenomenon detected.

Crediti immagine: NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA Acknowledgement: Alert images with classifications provided by ALeRCE and Lasair.

Italy is at the forefront of this hunt for the secrets of the cosmos through the National Institute of Astrophysics (INAF), which leads international collaborations to decipher this tsunami of data. It’s not just about cataloging stars, but about capturing events so rapid that they have been invisible until now. “What makes Rubin revolutionary is his ability to capture both rapid changes and the long-term evolution of the sky“, explains Rosaria Bonito, INAF researcher and INAF representative on the Board of Directors of the LSST Discovery Alliance. “Young stars, for example, can show sudden increases in brightness linked to accretion processes: short events, difficult to intercept without continuous monitoring. Rubin will allow us to observe them as they happen and follow their evolution for the entire duration of the survey, that is, for an entire decade“.

This constant monitoring, which will last ten years, promises to rewrite the astronomy books, providing definitive answers about the dark matter and dark energy that dominates the universe. With a flow of 10 terabytes of images per night managed by artificial intelligence and supercomputers, the observatory will produce more data in its first year than has been collected in the entire history of optical astronomy.”The extraordinary number of alerts that Rubin will produce represents an exciting challenge for both astronomers and software engineers“, points out Tom Matheson, director of the Community Science and Data Center, a program of NSF NOIRLab, and head of Time-Domain Services, which developed the ANTARES alert broker. “Broker teams have built systems that can operate rapidly on a large scale, allowing scientists to locate all the objects they’re interested in, as well as phenomena we’ve never observed before.“. The hunt is officially on: the sky is no longer a static image, but a battlefield of cosmic events ready to be discovered moment after moment.

Cover image credits: NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA/P. Marenfeld/J. Pinto