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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: 7:40  
clear_day Transit: 11:47  
SunsetSet: 15:53 south
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All Constellations » Serpens » 

Unukalhai - α Serpentis (alpha Serpentis)

Altitude: 31.9°   Azimuth: 235.2°   Direction: South-West

Unukalhai, also designated as α Serpentis (alpha Serpentis), is a multiple giant star in the constellation of Serpens.

Unukalhai visual magnitude is 2.65. Thanks to its high brightness, Unukalhai is clearly visible when observed from locations with dark skyes, and should be also quite easily visible from light polluted areas.

The table below summarizes the key facts about Unukalhai:


Unukalhai - α Serpentis (alpha Serpentis) is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 31.9°
Azimuth: 235.2°
Direction: South-West

Celestial coordinates and finder chart of Unukalhai

Unukalhai 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 Unukalhai are provided in the following table:

15h 44m 16s
+06° 25’ 32”

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

Finder chart Unukalhai - α Serpentis (alpha Serpentis) star
Simplified finder chart for Unukalhai - α Serpentis (alpha Serpentis).

Visibility of Unukalhai 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 Unukalhai - α Serpentis (alpha Serpentis) 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: 83.6°
Max altitude: 44.9°
Azimuth: 276.4°

Digitized Sky Survey image of Unukalhai

The image below is a photograph of Unukalhai 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 Unukalhai is 0.137 arcsec per year in Right Ascension and 0.047 arcsec per year in Declination and the associated displacement for the next 1000 years is represented with the red arrow.

Image of Unukalhai - α Serpentis (alpha Serpentis) star
DSS2 image of Unukalhai. The red arrow shows the motion of Unukalhai during the next 1000 years (2.28 arcmin in Right Ascension and 0.78 arcmin in declination);

Distance of Unukalhai from the Sun and relative movement

Unukalhai is distant 73.19 light years from the Sun and it is moving far from the Sun at the speed of 3 kilometers per second.

22.45 pc
73.19 ly
3 km/s
0.137 arcsec/year
0.047 arcsec/year

Spectral properties of Unukalhai

Unukalhai belongs to spectral class K2 and has a luminosity class of III corresponding to a giant star.


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

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

Unukalhai star system properties

Unukalhai is a visual double star which can be observed only with the help of very large telescopes. The table below shows key information about the Unukalhai double sysyem:

58.2 arcsec

Alternative designations of Unukalhai

α Serpentis
(alpha Serpentis)
24 Serpentis
Gl 596.2