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A Complete Guide to the Solar System and the Night Sky
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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
SunriseRise: 6:38  
clear_day Transit: 12:10  
SunsetSet: 17:43
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All Constellations » Sagittarius » 

21 Sagittarii

Altitude: -53.3°   Azimuth: 318.1°   Direction: North-West

21 Sagittarii is a double bright giant star in the constellation of Sagittarius.

21 Sagittarii visual magnitude is 4.81. Because of its moderate brightness, 21 Sagittarii should be easily visible from locations with dark skies, while it can be barely visible, or not visible at all, from skies affected by light pollution.

The proper motion of 21 Sagittarii is 0.006 arcsec per year in Right Ascension and -0.025 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of 21 Sagittarii star
DSS2 image of 21 Sagittarii. The red arrow shows the motion of 21 Sagittarii during the next 10000 years (1.00 arcmin in Right Ascension and -4.17 arcmin in declination);

Key facts about 21 Sagittarii

4.81
Bright giant

21 Sagittarii is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -53.3°
Azimuth: 318.1°
Direction: North-West

Celestial coordinates and finder chart of 21 Sagittarii

21 Sagittarii is situated close to the celestial equator, as such, it is at least partly visible from both hemispheres in certain times of the year. Celestial coordinates for the J2000 equinox as well as galactic coordinates of 21 Sagittarii are provided in the following table:

18h 25m 20s
-20° 32’ 30”
11.74°
-3.75°
Sagittarius

The simplified sky map below shows the position of 21 Sagittarii in the sky:

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

Visibility of 21 Sagittarii from your location

Location: Greenwich, United Kingdom edit_location_alt
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

Today's 21 Sagittarii rise, transit and set times from Greenwich, United Kingdom edit_location_alt are the following (all times relative to the local timezone Europe/London):

Azimuth: 110.5°
Max altitude: 18.0°
Azimuth: 249.5°

Distance of 21 Sagittarii from the Sun and relative movement

21 Sagittarii is distant 597.07 light years from the Sun and it is moving towards the Sun at the speed of 12 kilometers per second.

183.15 pc
597.07 ly
-12 km/s
0.006 arcsec/year
-0.025 arcsec/year

Spectral properties of 21 Sagittarii

21 Sagittarii belongs to spectral class K2 and has a luminosity class of II corresponding to a bright giant star.

-1.50
K2II
4104K

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

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

21 Sagittarii star system properties

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

4.81
8.41
3.6
1.7 arcsec

Alternative designations of 21 Sagittarii

21 Sagittarii
SAO186794
SAO186794