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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: 6:59  
clear_day Transit: 12:12  
SunsetSet: 17:25
sunny DaytimeWhat's Visible Now?
All Constellations » Scorpius » 


Altitude: 0.9°   Azimuth: 213.2°   Direction: South-South-West

HR6645 is a double hypergiant star in the constellation of Scorpius.

HR6645 visual magnitude is 6.66. Because of its reltive faintness, HR6645 should be visible only from locations with dark skyes, while it is not visible at all from skyes affected by light pollution.

The proper motion of HR6645 is 0.002 arcsec per year in Right Ascension and -0.011 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of HR6645 star
DSS2 image of HR6645. The red arrow shows the motion of HR6645 during the next 10000 years (0.33 arcmin in Right Ascension and -1.83 arcmin in declination);

Key facts about HR6645


HR6645 is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 0.9°
Azimuth: 213.2°
Direction: South-South-West

Celestial coordinates and finder chart of HR6645

HR6645 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 HR6645 are provided in the following table:

17h 51m 12s
-30° 33’ 25”

The simplified sky map below shows the position of HR6645 in the sky:

Finder chart HR6645 star
Simplified finder chart for HR6645.

Visibility of HR6645 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 HR6645 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: 120.6°
Max altitude: 8.0°
Azimuth: 239.4°

Distance of HR6645 from the Sun and relative movement

HR6645 is distant 684.87 light years from the Sun and it is moving towards the Sun at the speed of 9 kilometers per second.

210.08 pc
684.87 ly
-9 km/s
0.002 arcsec/year
-0.011 arcsec/year

Spectral properties of HR6645

HR6645 belongs to spectral class A0 and has a luminosity class of V corresponding to a hypergiant star.


The red dot in the diagram below shows where HR6645 is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of HR6645. Attribution: Richard Powell / CC BY-SA

HR6645 star system properties

HR6645 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 HR6645 double sysyem:

10.2 arcsec

Alternative designations of HR6645