PSR B1919+21 is a pulsar with a period of 1.3373 seconds and a pulse width of 0.04 seconds. Discovered by Jocelyn Bell Burnell on November 28, 1967, it is the first discovered radio pulsar. The power and regularity of the signals were briefly thought to resemble an extraterrestrial beacon, leading the source to be nicknamed LGM-1 (for "little green men").
Epoch J2000 (ICRS) Equinox J2000 (ICRS)
|Right ascension||19h 21m 44.815s|
|Declination||+21° 53′ 02.25″|
|Radius||~1.4 × 10−5 R☉|
In 1967, a radio signal was detected using the Interplanetary Scintillation Array of the Mullard Radio Astronomy Observatory in Cambridge, UK, by Jocelyn Bell. The signal had a 1.337302088331-second period and 0.04-second pulsewidth. It originated at celestial coordinates 19h 19m right ascension, +21° declination. It was detected by individual observation of miles of graphical data traces. Due to its almost perfect regularity, it was at first assumed to be spurious noise, but this hypothesis was promptly discarded. The discoverers jokingly named it little green men 1 (LGM-1), considering that it may have originated from an extraterrestrial civilization, but Bell soon ruled out extraterrestrial life as a source after discovering a similar signal from another part of the sky.
The original signal turned out to be radio emissions from the pulsar CP 1919, and was the first one recognized as such. Bell noted that other scientists could have discovered pulsars before her, but their observations were either ignored or disregarded. Researchers Thomas Gold and Sir Fred Hoyle identified this astronomical object as a rapidly rotating neutron star immediately upon their announcement.
We did not really believe that we had picked up signals from another civilization, but obviously the idea had crossed our minds and we had no proof that it was an entirely natural radio emission. It is an interesting problem – if one thinks one may have detected life elsewhere in the universe[,] how does one announce the results responsibly? Who does one tell first?
When Hewish and Martin Ryle received the Nobel Prize in physics in 1974 for their work in radio astronomy and pulsars, Hoyle argued that Jocelyn Bell Burnell should have been a co-recipient of the prize.
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