Webb Telescope Detects Record-Breaking GRB 250702B: A Cosmic Blast Defying Five Decades of Physics

Webb and global telescopes investigate GRB 250702B, a record-breaking 7-hour explosion that reveals new ways black holes may destroy stars.

By: AXL Media

Published: Mar 30, 2026, 11:16 AM EDT

Source: Information for this report was sourced from NASA and Rutgers University.

An Explosion Without Precedent in Modern Astronomy

Gamma-ray bursts (GRBs) are typically the most violent and energetic flashes in the universe, usually signaling the collapse of a massive star into a black hole. However, these events are almost always fleeting, fading within seconds or a few minutes. GRB 250702B has shattered this paradigm by maintaining its high-energy emission for over seven hours. Huei Sears, a postdoctoral researcher at Rutgers University, noted that the event displayed properties so extreme they defy current theoretical models, including mysterious X-ray activity that began a full day before the primary burst.

Global Collaboration Spans the Electromagnetic Spectrum

Because of the burst's intensity and duration, no single instrument could capture the full scope of the event. Detection began with NASA's Fermi Gamma-ray Space Telescope on July 2, which triggered a rapid global response. Teams utilized the Einstein Probe in China, the National Science Foundation’s Very Large Array (VLA), and the James Webb Space Telescope to collect data across X-ray, infrared, and radio wavelengths. Interestingly, the explosion remained entirely invisible to telescopes operating in ordinary visible light, hidden behind thick blankets of cosmic dust.

Contradictory Models: Tidal Disruption vs. Stellar Mergers

The scientific community is currently evaluating three primary theories to explain the seven-hour outburst: