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public  Greenwich, UK Greenwich, UK  ⓘ
TimezoneEurope/London
Sunrise: 7:20 
Transit: 12:46 
Sunset: 18:11
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All Constellations » Cassiopeia » 

21 Cassiopeiae

Above the horizon.  Circumpolar today
Alt: 37.57°   Az: 7.46°   Direction: North

21 Cassiopeiae is a variable and double sub-giant star of spectral class A2 in the constellation of Cassiopeia.

21 Cassiopeiae visual magnitude is 5.66. Because of its faintness, 21 Cassiopeiae is visible to the naked eye only from locations with very dark skies, while it is not visible at all from skies affected by light pollution.

Image of 21 Cassiopeiae star
DSS2 image of 21 Cassiopeiae. The red arrow shows the motion of 21 Cassiopeiae during the next 10000 years (-3.00 arcmin in Right Ascension and -4.33 arcmin in declination);

Celestial Coordinates

Apparent

00h 47m 20s
+75° 07’ 23”
13h 34m 30s
14h 21m 51s

J2000

00h 45m 38s
+74° 59’ 17”

Galactic Coordinates

122.55°
12.12°

Finder Chart

Finder chart 21 Cassiopeiae star
Simplified finder chart for 21 Cassiopeiae.

Magnitude, Color, Spectral Class

5.66
Sub-giant

0.91
A2IV
9542K

The red dot in the diagram below shows where 21 Cassiopeiae is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of 21 Cassiopeiae. Attribution: Richard Powell / CC BY-SA

Star System Properties

21 Cassiopeiae is a visual double star which can be observed with the help of small or medium telescopes. The table below shows key information about the 21 Cassiopeiae double sysyem:

5.66
11.16
5.5
36 arcsec

Distance, Radial Speed, Proper Motion

21 Cassiopeiae is distant 290.04 light years from the Sun and it is moving far from the Sun at the speed of 9 kilometers per second.

88.97
290.04
9 km/s
-0.018 arcsec/y
-0.026"/y

Alternative Designations

21 Cassiopeiae
SAO4216
SAO4216

Visibility from Your Location

21 Cassiopeiae is circumpolar and transits at 23:19 UTC (altitude: 66.4°)