COSMOS / CONSTELLATIONS / CAS
Cassiopeia (Queen)
The Queen. IAU abbreviation Cas. One of the 48 classical constellations listed by Ptolemy in the Almagest in the 2nd century AD.
STAR CHART
KEY FACTS
- IAU abbreviation
- Cas
- Latin name / genitive
- Cassiopeia / Cassiopeiae
- Position
- Right ascension ≈ 0 h 56 m; declination +47° to +78°
- 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 2 December.
- Number of stars
- 161 stars brighter than magnitude 6.5 in the catalogue; 31 brighter than 5 and 8 brighter than 4.
INTERACTIVE LAB
Where is Cassiopeia 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 2 December).
MYTH, HISTORY AND OBSERVING
Queen Cassiopeia, Andromeda’s vain mother. Five bright stars form a conspicuous “W” that is visible all year from Türkiye. Tycho Brahe’s supernova of 1572 and the strong radio source Cassiopeia A, a supernova remnant, both lie here.
BRIGHTEST STARS
| Star | Magnitude | Distance (light-years) | Spectral type |
|---|---|---|---|
| Cih | 2.15 | 549 | B0IV:evar |
| Schedar | 2.24 | 228 | K0II-IIIvar |
| Caph | 2.28 | 55 | F2III-IV |
| Ruchbah | 2.66 | 99 | A5Vv |
| Segin | 3.35 | 412 | B2pvar |
| Achird | 3.46 | 19 | G0V |
| Fulu | 3.69 | 593 | B2IV |
| 50 Cas | 3.95 | 157 | A2V |
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.