Astronomers at the University of Warwick, working with the citizen-science initiative Kilonova Seekers, have identified an exceptionally bright cataclysmic variable star after its luminosity in the night sky intensified about 2,500-fold within hours. The system, catalogued GOTO0650, was first flagged on 4 July 2025 when volunteers comparing images from the twin GOTO telescopes spotted the sudden flare less than four hours after it occurred. GOTO0650 consists of a white dwarf drawing material from a close companion star. Researchers say the outburst likely marks the rare “period-bounce” stage—an evolutionary endgame in which mass-transfer dynamics shift as the binary’s orbital period lengthens. Such systems are difficult to catch in real time, making the discovery valuable for modelling the late lives of interacting binaries. The rapid alert allowed professional and amateur astronomers to secure spectroscopy, X-ray and ultraviolet observations while the star remained near peak brightness. Tom Killestein, co-director of Kilonova Seekers, said the find demonstrates how crowdsourced analysis can accelerate time-critical science. It is the project’s first major discovery and underscores the growing role of public participation in monitoring transient cosmic events.