Astronomers have finally decoded the origin of a powerful seven hour signal from deep space, a blast so persistent that it immediately stood out from the universe’s usual fireworks. The event, catalogued as GRB 250702B, has now been identified as the longest lasting gamma ray burst ever recorded, forcing researchers to rethink how some of the most extreme explosions in the cosmos actually work. Instead of a fleeting flash, this was a sustained cosmic beacon, and its explanation is reshaping ideas about dying stars, exotic binaries and the limits of known physics.
Gamma ray bursts are already among the most violent events since the Big Bang, but a signal that refuses to fade for hours hints at something even stranger happening at their cores. By combining rapid alerts from space telescopes with follow up observations on the ground, teams have pieced together a story that links GRB 250702B to jets moving at nearly the speed of light and to a growing family of puzzling long lived signals, from slow radio pulses in the Milky Way to mysterious long period transients.
The seven hour blast that broke the gamma ray record
When Astronomers first registered GRB 250702B, they knew immediately that this was no ordinary flash. Typical gamma ray bursts, or GRBs, last from fractions of a second to a few minutes before fading into afterglow, but this event kept pouring out high energy radiation for more than seven hours, making it the longest lasting GRB ever seen and a clear outlier that, as one analysis put it, needs a novel physical explanation. Early reports on the signal stressed that Astronomers had detected a strong signal from space lasting seven hours and that Now, after months of modelling, they may have worked out what it was, a Gamma event that stretches current theories of how these explosions start and stop, as detailed in one account.
In 2025, Astronomers had already been on alert for unusual high energy events when they detected a blast from space that lasted seven hours, a duration so extreme that it immediately raised questions about the physics behind gamma ray bursts and whether existing models could cope with such a marathon explosion. Follow up work on GRB 250702B, described in another detailed study, showed that the event’s light curve did not fit neatly into the usual “short” or “long” GRB categories, instead forming a plateau of emission that persisted far longer than expected. That persistence is what turned a single detection into a major puzzle, and it is why GRB 250702B is now treated as a benchmark case for extreme cosmic explosions.
What makes GRB 250702B so different from ordinary cosmic blasts
To understand why GRB 250702B is so disruptive, it helps to recall what a standard GRB looks like. A gamma ray burst is the most energetic type of explosion in the universe since the Big Bang, typically detected once every day somewhere on the sky, and in most cases the prompt emission is over in seconds or minutes before fading into lower energy afterglow. Detailed imaging of the seven hour event showed a narrow jet of material moving at up to 99 percent of the speed of light, a feature that matches the behaviour of other GRBs but on a far longer timescale, as highlighted in one analysis. That combination, familiar jet physics but unprecedented duration, is what makes the event unlike anything scientists had seen before.
There are two processes that are known to lead to GRBs. Most originate from the collapse of a rapidly rotating, massive star, while others are triggered when compact objects such as neutron stars merge, and Thes scenarios usually produce bursts that shut off quickly once the central engine runs out of fuel. In the case of GRB 250702B, however, the central engine appears to have stayed active for hours, suggesting either a very long lived accretion disk around a newborn black hole or a highly magnetised neutron star that kept pumping energy into the jet. That need for an extended power source is why researchers argue that the seven hour signal, described in detail in one interview, may point to new physics in how stellar cores collapse and how relativistic jets are sustained.
Decoding the signal: from space telescopes to ground based observatories
Once the seven hour signal was flagged, the race was on to capture as much data as possible across the electromagnetic spectrum. Space based detectors first registered the high energy flash, then ground based facilities such as Gemini Observatory and Cerro Tololo Inter-American Observatory were brought to bear, providing optical and infrared follow up that helped pin down the burst’s distance and environment. A detailed video briefing described how a New record alert announced that Astronomers had detected the longest ever GRB and that GRB 250702B lasted over 7 hours, with teams using Gemini and CTIO data to constrain the origin of this event, as outlined in a briefing.
High resolution imaging and spectroscopy showed that the burst originated in a distant galaxy, consistent with other long GRBs that trace the deaths of massive stars in star forming regions. At the same time, detailed modelling of the light curve and spectrum, described in several technical reports, indicated that the jet structure and energy budget were extreme even by GRB standards. I see this multi wavelength campaign as a template for future work on unusual transients, combining rapid alerts from space with flexible ground based follow up to decode signals that do not fit standard categories.
Slow cosmic signals: how a binary system solved another mystery
While GRB 250702B pushed the limits of high energy astrophysics, another class of long lived signals has been puzzling researchers at much lower frequencies. Cosmic radio pulses repeating every few minutes or hours, known as long period transients, have challenged standard models of neutron stars because their slow repetition rates and longevity do not match the behaviour of typical pulsars or magnetars. A recent overview of these Cosmic signals described how some sources repeat every few minutes, while a uniquely long lived example shows a pattern that repeats every nine hours, highlighting just how diverse these slow transients can be, as outlined in one summary.
One breakthrough came with GPM J1839-10, the name of the longest LPT known, with a 21 minute period, observed in the Milky Way and now shown to be part of a binary system. Detailed work demonstrated that GPM J1839-10 is a white dwarf–M-dwarf binary, with the white dwarf’s magnetic field and rotation driving the radio pulses, a configuration that suggests such systems may be more common than previously thought, as explained in a technical note. Astronomers have identified this long period cosmic radio source, GPM J1839-10, as a white dwarf–M-dwarf binary system, a result that was highlighted in a separate report, and it shows how careful timing and multi wavelength observations can turn a mysterious periodic signal into a well understood astrophysical system.
Linking extreme explosions and long period transients
At first glance, a seven hour gamma ray blast and a 21 minute radio pulse from a white dwarf binary might seem unrelated, but I see a common thread in how both discoveries expand the known parameter space of cosmic transients. In each case, the signal’s duration and repetition pattern fell far outside the norms that guided earlier searches, forcing Astronomers to revisit assumptions about what kinds of objects can produce high energy jets or coherent radio beams. A detailed overview of GPM J1839-10 noted that GPM J1839-10 is the name of the longest LPT known, with a 21 min period, observed in the Milky Way and that this discovery implies such long period systems may be more common than previously thought, as one overview put it, while another summary of these Cosmic radio pulses stressed that long period transients have puzzled Astronomers since their discovery, as described in a separate analysis.
More from Morning Overview
*This article was researched with the help of AI, with human editors creating the final content.
