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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
north SunriseRise: 7:48  
clear_day Transit: 11:49  
SunsetSet: 15:50 south
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All Constellations » Sagittarius » 

Arkab Prior - β1 Sagittarii (beta1 Sagittarii)

Altitude: -21.8°   Azimuth: 224.8°   Direction: South-West

Arkab Prior, also designated as β1 Sagittarii (beta1 Sagittarii), is a double main-sequence star in the constellation of Sagittarius.

Arkab Prior visual magnitude is 4.01. Because of its moderate brightness, Arkab Prior should be easily visible from locations with dark skyes, while it can be barely visible, or not visible at all, from skyes affected by light pollution.

The table below summarizes the key facts about Arkab Prior:


Arkab Prior - β1 Sagittarii (beta1 Sagittarii) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -21.8°
Azimuth: 224.8°
Direction: South-West

Celestial coordinates and finder chart of Arkab Prior

Arkab Prior is situated south of the celestial equator, as such, it is more easily visible from the southern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of Arkab Prior are provided in the following table:

19h 22m 38s
-44° 27’ 32”

The simplified sky map below shows the position of Arkab Prior in the sky:

Finder chart Arkab Prior - β1 Sagittarii (beta1 Sagittarii) star
Simplified finder chart for Arkab Prior - β1 Sagittarii (beta1 Sagittarii).

Visibility of Arkab Prior from your location

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

Arkab Prior - β1 Sagittarii (beta1 Sagittarii) is currently not visible from Greenwich, United Kingdom edit_location_alt

Digitized Sky Survey image of Arkab Prior

The image below is a photograph of Arkab Prior from the Digitized Sky Survey 2 (DSS2 - see the credits section) taken in the red channel. The area of sky represented in the image is 0.5x0.5 degrees (30x30 arcmins). The proper motion of Arkab Prior is 0.009 arcsec per year in Right Ascension and -0.02 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of Arkab Prior - β1 Sagittarii (beta1 Sagittarii) star
DSS2 image of Arkab Prior. The red arrow shows the motion of Arkab Prior during the next 10000 years (1.50 arcmin in Right Ascension and -3.33 arcmin in declination);

Distance of Arkab Prior from the Sun and relative movement

Arkab Prior is distant 378.19 light years from the Sun and it is moving towards the Sun at the speed of 11 kilometers per second.

116.01 pc
378.19 ly
-11 km/s
0.009 arcsec/year
-0.02 arcsec/year

Spectral properties of Arkab Prior

Arkab Prior belongs to spectral class B9 and has a luminosity class of V corresponding to a main-sequence star.


The red dot in the diagram below shows where Arkab Prior is situated in the Hertzsprung–Russell diagram.

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

Arkab Prior star system properties

Arkab Prior is a visual double star which can be observed with binoculars or small telescopes. The table below shows key information about the Arkab Prior double sysyem:

28.3 arcsec

Alternative designations of Arkab Prior

Arkab Prior
β1 Sagittarii
(beta1 Sagittarii)