COSMOS / CONSTELLATIONS / CEP
Cepheus (King)
The King. IAU abbreviation Cep. One of the 48 classical constellations listed by Ptolemy in the Almagest in the 2nd century AD.
STAR CHART
KEY FACTS
- IAU abbreviation
- Cep
- Latin name / genitive
- Cepheus / Cephei
- Position
- Right ascension ≈ 22 h 48 m; declination +55° to +87°
- Visibility from Türkiye
- From Ankara most of it never sets (circumpolar); visible all year.
- Best time to observe
- Visible all year; highest at 21:00 Türkiye time around 30 October.
- Number of stars
- 159 stars brighter than magnitude 6.5 in the catalogue; 22 brighter than 5 and 6 brighter than 4.
INTERACTIVE LAB
Where is Cepheus tonight?
Seen from Ankara, most of this constellation never sets. Drag the time slider through the night to watch it circle the pole; the “Best night” button jumps to the date when it is highest at 21:00 (around 30 October).
MYTH, HISTORY AND OBSERVING
King Cepheus of Ethiopia, husband of Cassiopeia and father of Andromeda. Delta Cephei gave its name to the Cepheid variables, a cosmic yardstick for measuring distances. Mu Cephei, William Herschel’s “Garnet Star”, is one of the largest stars known.
BRIGHTEST STARS
| Star | Magnitude | Distance (light-years) | Spectral type |
|---|---|---|---|
| Alderamin | 2.45 | 49 | A7IV-V |
| Errai | 3.21 | 46 | K1IV |
| Alfirk | 3.23 | 685 | B2IIIv |
| ζ Cep | 3.39 | 836 | K1Ibv |
| η Cep | 3.41 | 47 | K0IV |
| ι Cep | 3.50 | 115 | K0III |
| δ Cep | 4.07 | 865 | G2Ibvar |
| ε Cep | 4.18 | 85 | F0IV |
Magnitude: apparent brightness; the smaller the number, the brighter the star. Distances derive from parallax measurements and are uncertain for distant stars. Source: HYG v4.1 star catalogue (CC BY-SA 4.0).
SOURCES
Position, visibility and best observing time were computed approximately for this page from the catalogue stars (Ankara, 39.9° N). The 88 constellations were adopted by the IAU in 1922; their boundaries were drawn by Eugène Delporte in 1930.