LGM-1, formally catalogued as PSR B1919+21, is the first neutron star discovered. Dame Jocelyn Bell Burnell, a graduate student at Cambridge University, found a regular signal in the radio spectrum that had a regular period of about 1.3 seconds. Burnell labeled the discovery "little green men 1," giving to the remote possibility that the signal was not naturally occurring.

Following up on her discovery, Bell Burnell later found a similar repeating radio signal in a different sector of the galaxy. The second discovery, she said in a 21st century television interview, "scotched the little green men hypothesis ... Because it's highly unlikely there's two lots of little green men, on opposite sides of the universe, both deciding to signal to a rather inconspicuous planet, Earth, at the same time, using a daft technique and a rather commonplace frequency."

The first human to visit LGM-1 and return with the system cartographics data was CMDR Zoink. The pulsar and its companion, a G-class main sequence star, are about 1.77 billion years old. LGM-1 has 1.40 solar masses, placing it near the lower bound of neutron star masses; its radius is 8.9 km, making it four times the size of Cambridge or about as large as the District of Columbia. Its companion star is about 0.91 solar mass and 0.96 solar radii. The two stars orbit their common barycentre once every 7,150 years.

The system lies about 600 light-years from the Traikeou AA-A h2 nebula, making it a potential sidestop for anyone visiting the nebula on their way to the Milky Way's Temple region.