In July 2025, the global scientific community registered an extraordinary cosmic phenomenon: a gamma-ray burst officially designated GRB 250702B. This event immediately captured unprecedented attention due to its unusually prolonged nature and a sequence of recurring pulses that spanned a full day. The initial detection of this powerful energy emission occurred on July 2, 2025. NASA’s orbital telescope, Fermi, first registered a series of flares originating from the same remote source over several hours.
What sets GRB 250702B apart is its temporal structure, which fundamentally challenges established astrophysical models. While most typical gamma-ray bursts last anywhere from milliseconds to a few minutes, this particular signal persisted for approximately a day, or nearly seven hours, according to some measurements, cementing its status as the longest recorded burst to date. Astrophysicists generally theorize that such bursts result from the catastrophic collapse of a massive star into a black hole—one of the most energetic processes known in the universe. Crucially, however, the observed repetition of the event defies standard explanations, as the source of such a cataclysm is not expected to survive the initial explosion.
The complexity of the signal necessitated a broad international effort. Experts from the European Space Agency (ESA), University College Dublin, and Radboud University quickly joined the analysis. Subsequent investigations, including those utilizing the European Southern Observatory’s Very Large Telescope (VLT), were crucial in pinpointing the exact location of the source. Initially, researchers speculated that the burst originated within the plane of the Milky Way galaxy, which would have been highly unusual for such an event.
However, observations conducted by both the VLT and the Hubble telescope ultimately confirmed that GRB 250702B originated in a different, vastly distant galaxy. The latest calculations place the source at an estimated distance of about 8 billion light-years away. Furthermore, the event, which included related flares such as GRB 250702D and GRB 250702, exhibited clear signs of periodicity. This suggests the possibility that the process was triggered by an object orbiting the newly formed black hole, introducing a novel mechanism for these powerful explosions.
This discovery marks a significant new chapter in our understanding of the mechanisms behind supernovae formation and the collapse of massive stars. GRB 250702B provides a unique and rare opportunity to study the long-lived echoes of catastrophic cosmic phenomena. Scientists are maintaining continuous observation of the explosion site, employing both the VLT and the powerful James Webb Telescope, as they strive to decipher the true nature of this extraordinary cosmic message and unlock the secrets held within its repeating pattern.