At night, while most people sleep, the giant dish of the Green Bank radio telescope in West Virginia keeps listening to the sky. Over 24,186 hours, that's nearly three years of continuous observation, it caught 50 pulsars and three fast radio bursts. Fast radio bursts are short but incredibly powerful radio pulses from distant galaxies. They last only a few milliseconds, but in that time they release as much energy as the Sun emits in several days.

Among the pulsars caught, dead stars that spin and send out radio beams like lighthouses, was one completely new. It's named PSR J0039+5407. It rotates once every 2.2 seconds — slower than most known pulsars. But the strangest thing: this pulsar goes silent 70–80% of the time. Astronomers call this behavior 'nulling'—as if the lighthouse turns its light on and off without any visible reason.

The three fast radio bursts the telescope caught turned out to be from already known sources: they had been observed before. The main difficulty in finding new bursts is the telescope's single beam. It looks at only one point in the sky, and earthly interference (from radars, satellites, microwave ovens) can easily masquerade as cosmic signals. One such case is particularly telling: a pulse passed all the filters, but on closer inspection turned out to be part of a longer narrowband signal of unknown origin. It's unclear whether it's earthly or celestial.

The telescope keeps listening. Perhaps the next fast radio burst will be a new one, and then we'll learn more about what's happening in distant galaxies.