The obsolete constellation Cerberus, The Three-Headed Snake, is a northern constellation bordering Hercules, Ophiuchus, Aquila, Sagitta, Vulpecula and Lyra.

Cerberus was created in the 17th century by Johannes Hevelius, and its stars are now included in Hercules. It spans 15 degrees of the zodiac in the Signs of Sagittarius and Capricorn.

Abbreviation: Cer
Genitive: Cerberi ^[1]

Constellation Cerberus Stars

2000	2050	Star	Name	Sp. Class	Mag.	Orb
00♑01	00♑43	93 Her		K0	4.67	1°00′
00♑29	01♑11	95 Her		G5	4.26	1°20′
02♑51	03♑33	102 Her		B2	4.37	1°10′
07♑48	08♑30	109 Her	Cladus	K2	3.85	1°30′

Cerberus Astrology

Robson

CERBERUS.

History and Legend. This constellation, which is not now recognized, was probably added by Hevelius in 1690. It represents the three-headed monster that guarded the gates of Hades and was brought to the upper world by Hercules. The figure depicts it as held by Hercules, in which the constellation is now merged. According to some accounts, it is the serpent slain by Hero that infested the country around Taenarum.

Influence. Cerberus is said to cause faithfulness, devotion, industry and watchfulness, and to restrain from evil, but to give danger of poison. ^[2]

Allen

Cerberus. This sub-constellation, a former adjunct of Hercules, but now entirely disregarded by astronomers, is supposed to have originated with Hevelius in his Firmamentum Sobiescianum, although Flammarion asserts that it was on the sphere of Eudoxos with the Branch. The 4th- to 5th‑magnitude stars that Hevelius assigned to it are Flamsteed’s 93, 95, 96, and 109, lying half-way between the head of Hercules and the head of the Swan.

The royal poet James I designated the infernal Cerberus as “the thrie headed porter of hell,” and the heavenly one has been so figured, although with serpents’ darting tongues; but the abode and task of the creature would seem to render very inappropriate his transfer to the sky, so that it probably was only made for the purpose of mythological completeness, as the death of this watch-dog of Hades fitly rounded out the circle of Hercules’ twelve labours.

Others have said that the figure typified the serpent destroyed by the Hero while it was infesting the country around Taenarum, the Μέτωπον of Greece, the modern Cape Matapan.

Some of the stars of Cerberus were known in China as Too Sze, the Butcher’s Shop; and others as Meen Too, a Cloth Measure. ^[3]

References

1. SkyEye: Cerberus
2. Fixed Stars and Constellations in Astrology, Vivian E. Robson, 1923, p.37-38.
3. Star Names: Their Lore and Meaning, Richard H. Allen, 1889, p.159-160.