Your Guide to the Solar System and the Night Sky
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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 4:50  
clear_day Transit: 12:56  
SunsetSet: 21:03 south
sunny DaytimeWhat's Visible Now
All Constellations » Cygnus » 


HR8166 is a multiple sub-giant star in the constellation of Cygnus.

HR8166 visual magnitude is 5.68. Because of its reltive faintness, HR8166 should be visible only from locations with dark skyes, while it is not visible at all from skyes affected by light pollution.

The table below summarizes the key facts about HR8166:

HR8166 is above the horizon from Greenwich, United Kingdom edit_location_alt. Altitude: 3°.

Celestial coordinates and finder chart of HR8166

HR8166 is situated north of the celestial equator, as such, it is more easily visible from the northern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of HR8166 are provided in the following table:

21h 20m 50s
+32° 27’ 10”

The simplified sky map below shows the position of HR8166 in the sky:

Finder chart HR8166 star
Simplified finder chart for HR8166.

Visibility of HR8166 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 HR8166 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: 57.5°
Max altitude: 71.0°
Azimuth: 302.5°
HR8166 is above the horizon from Greenwich, United Kingdom

Digitized Sky Survey image of HR8166

The image below is a photograph of HR8166 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 HR8166 is 0.053 arcsec per year in Right Ascension and -0.033 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of HR8166 star
DSS2 image of HR8166. The red arrow shows the motion of HR8166 during the next 10000 years (8.83 arcmin in Right Ascension and -5.50 arcmin in declination);

Distance of HR8166 from the Sun and relative movement

HR8166 is distant 238.83 light years from the Sun and it is moving towards the Sun at the speed of 29 kilometers per second.

73.26 pc
238.83 ly
-29 km/s
0.053 arcsec/year
-0.033 arcsec/year

Spectral properties of HR8166

HR8166 belongs to spectral class G8 and has a luminosity class of IV corresponding to a sub-giant star.


The red dot in the diagram below shows where HR8166 is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of HR8166. Attribution: Richard Powell / CC BY-SA

HR8166 star system properties

HR8166 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 HR8166 double sysyem:

2.1 arcsec

Alternative designations of HR8166