Scientists Identify 7-Hour GRB 250702B as Longest Gamma-Ray Burst Ever Recorded
Updated
Updated · Sky at Night Magazine · May 26
Scientists Identify 7-Hour GRB 250702B as Longest Gamma-Ray Burst Ever Recorded
2 articles · Updated · Sky at Night Magazine · May 26
GRB 250702B lasted about 25,000 seconds—roughly seven hours—making it the longest gamma-ray burst ever recorded after astronomers combined data from five high-energy telescopes.
Three bursts from the same patch of sky led researchers to conclude the event could not be explained by standard gamma-ray-burst origins such as collapsing massive stars or merging neutron stars.
The team says the best fit is a helium merger, in which a stellar-mass black hole plunges into an expanded helium star, rapidly consumes it and powers an unusually long-lived jet.
Extreme-duration bursts may be undercounted because they are dimmer and harder for instruments tuned to short, bright flashes to detect, limiting how far away they can be seen.
A new gamma-ray survey telescope, COSI, is due to launch in 2027 and is being prepared to better detect such long events, which could clarify how rare these outbursts are.
Last year's seven-hour stellar explosion revealed a new cosmic monster. How many more have we been missing all along?
A black hole devouring a star, or a star shredded by gravity? Which theory explains 2025's record-breaking cosmic blast?
The Longest Gamma-Ray Burst Ever Recorded: GRB 250702B’s Seven-Hour Cosmic Explosion Redefines Astrophysics
Overview
GRB 250702B, discovered on July 2, 2025, stands out as the longest gamma-ray burst ever recorded, lasting over 25,000 seconds—more than seven hours. This ultra-long event, identified through a global collaboration using advanced observatories, challenges existing theories about how gamma-ray bursts form. Its extraordinary duration and unique features have provided new insights into these rare cosmic explosions, pushing scientists to rethink traditional models and explore new explanations for such powerful and long-lasting phenomena in the universe.