[2] It is located in the constellation Lynx and it was discovered in Low-Frequency Array (LOFAR) data by a team of astronomers led by Martijn Oei.

[1][5] Alcyoneus was first reported in a paper published in February 2022 by Martijn Oei and colleagues after obtaining results from the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS), an interferometric radio survey of the Northern Sky, as part of a search that resulted in the discovery of over 8,000 new giant radio galaxies.

In the case of Alcyoneus, the host galaxy does not host a quasar and is relatively quiescent, with spectral imaging from the Sloan Digital Sky Survey's 12th data release (SDSS DR12) suggesting a star formation rate of only 0.016 solar masses per year (1.6×10−2 M☉/a).

This classifies it as a low excitation radio source, with Alcyoneus obtaining most of its energy due to the relativistic process of the central galaxy's jet rather than radiation from its active galactic nucleus.

In comparison to other known giant radio galaxies, Alcyoneus does not appear to have a particularly massive stellar population or central black hole, or particularly powerful jet streams.