NASA missions identify unusual Gamma Ray burst with record duration

On July 2, 2025, NASA satellites detected an extraordinary gamma-ray burst (GRB) that persisted for multiple days, setting a record for duration among known cosmic explosions.

Named GRB 250702B, the event challenges typical classifications, as most GRBs last only seconds to minutes.

According to NASA, researchers suggest the outburst resulted from a black hole consuming a star, though the exact mechanism remains under investigation.

Data indicate either a mid-sized black hole shredding a star or a smaller black hole merging with a companion star.

Findings were presented by Eliza Neights at George Washington University and NASA’s Goddard Space Flight Center.

Detection and observation

The initial gamma-ray emission lasted at least seven hours, nearly double the previous GRB record.

The burst was first observed by the Gamma-ray Burst Monitor on NASA’s Fermi Gamma-ray Space Telescope, triggering multiple times within three hours.

It was simultaneously detected by the Burst Alert Telescope on NASA’s Neil Gehrels Swift Observatory, the Russian Konus instrument on NASA’s Wind mission, the Gamma-Ray and Neutron Spectrometer on Psyche, and Japan’s Monitor of All-sky X-ray Image instrument aboard the International Space Station.

Eric Burns of Louisiana State University noted that only through coordinated measurements from these instruments could researchers fully capture the event.

Additional observations in X-rays came from China’s Einstein Probe, Swift’s X-Ray Telescope, and NASA’s Chandra X-Ray Observatory.

Swift identified the burst in the constellation Scutum on July 3, with X-ray signals observed a day earlier.

Ground-based telescopes, including Keck, Gemini, and the Very Large Telescope, suggested a galaxy at the burst location.

NASA’s Hubble Space Telescope confirmed a distant galaxy, while the James Webb Space Telescope provided detailed imaging through dust lanes surrounding the source, as reported by Huei Sears of Rutgers University.

Energy and host galaxy characteristics

The burst released energy equivalent to a thousand Suns shining over 10 billion years, according to Benjamin Gompertz of the University of Birmingham.

Light from the explosion began traveling 8 billion years ago. Swift, Chandra, and NASA’s NuSTAR provided extended X-ray monitoring, revealing flares up to two days post-discovery.

Brendan O’Connor of Carnegie Mellon University stated that the continued flares indicate prolonged accretion by the black hole.

Spectroscopic observations from Webb did not detect a supernova, which typically follows stellar collapse GRBs, though dust may have obscured any explosion.

Jonathan Carney of the University of North Carolina reported that the host galaxy is unusually large for a GRB, with more than twice the mass of the Milky Way.

Possible mechanisms

Researchers consider two main scenarios for GRB 250702B. One involves an intermediate-mass black hole with a few thousand solar masses that disrupted a star via tidal forces.

The second model describes a smaller black hole, approximately three times the mass of the Sun, merging with a dense helium star companion.

In both cases, matter from the star formed a disk around the black hole, producing X-ray emission followed by gamma-ray jets as material was consumed.

NASA's​‍​‌‍​‍‌​‍​‌‍​‍‌ fleet of observatories and instruments, among them Fermi, Swift, Chandra, NuSTAR, Hubble, and Webb, were instrumental in gathering extensive data.

The results have been made available to the public or submitted to journals such as Monthly Notices of the Royal Astronomical Society, The Astrophysical Journal Letters, and so on.

While on the ground, astronauts and scientists are benefiting from the partnerships with the European Space Agency, the Canadian Space Agency, the Italian Space Agency, and several universities and research institutions.

GRB 250702B is the farthest source of a gamma-ray burst (GRB) that has lasted for the most extended time, with unbroken observation enabling the in-depth study of the X-ray and gamma-ray characteristics.

This occurrence illustrates the spectrum of scenarios in which black holes can interact and thus, eventually, emit gamma rays for a prolonged period, as evidenced by the ensemble of NASA's space-based and ground-based observatories that worked in ​‍​‌‍​‍‌​‍​‌‍​‍‌concert.

Stay tuned for more updates.