The end of an era

Gaia has concluded its sky-scanning mission. After more than a decade of continuous operation, the spacecraft ceased regular observations on January 15, 2025. The immense trove of data it collected has only been partially released so far, and the effort toward a comprehensive data release will span several more years. With its unprecedented precision and a commitment to open data, Gaia has revolutionized numerous fields in astronomy and astrophysics. Its primary achievement, the Gaia catalog, has quickly become a cornerstone resource for the scientific community.

A less widely known yet invaluable contribution of Gaia was its alert system for variable objects and transient phenomena. By continuously scanning the sky, Gaia could swiftly detect and report new transients. These discoveries were analyzed and classified—often manually—by the Gaia Photometric Science Alerts Team, led by Simon Hodgkin at Cambridge University, UK.

The last Gaia alert was Gaia25aeh, detected on 2025-01-15 00:59:00. Gaia alerts are also available on Astro-COLIBRI (e.g. TNS2025oj, the official IAU name for the last alert Gaia25aeh)

Credit: ESA/Gaia/DPAC, Milky Way impression by Stefan Payne-Wardenaar