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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: 7:47  
clear_day Transit: 11:49  
SunsetSet: 15:50 south
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All Constellations » Ophiuchus » 

Yed Prior - δ Ophiuchi (delta Ophiuchi)

Altitude: 30.8°   Azimuth: 209.5°   Direction: South-South-West

Yed Prior, also designated as δ Ophiuchi (delta Ophiuchi), is a variable and double hypergiant star in the constellation of Ophiuchus.

Yed Prior visual magnitude is 2.74. Thanks to its high brightness, Yed Prior 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 Yed Prior:


Yed Prior - δ Ophiuchi (delta Ophiuchi) is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 30.8°
Azimuth: 209.5°
Direction: South-South-West

Celestial coordinates and finder chart of Yed Prior

Yed Prior 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 Yed Prior are provided in the following table:

16h 14m 20s
-03° 41’ 39”

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

Finder chart Yed Prior - δ Ophiuchi (delta Ophiuchi) star
Simplified finder chart for Yed Prior - δ Ophiuchi (delta Ophiuchi).

Visibility of Yed Prior 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 Yed Prior - δ Ophiuchi (delta Ophiuchi) 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: 93.7°
Max altitude: 34.8°
Azimuth: 266.3°

Digitized Sky Survey image of Yed Prior

The image below is a photograph of Yed 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 Yed Prior is -0.044 arcsec per year in Right Ascension and -0.143 arcsec per year in Declination and the associated displacement for the next 1000 years is represented with the red arrow.

Image of Yed Prior - δ Ophiuchi (delta Ophiuchi) star
DSS2 image of Yed Prior. The red arrow shows the motion of Yed Prior during the next 1000 years (-0.73 arcmin in Right Ascension and -2.38 arcmin in declination);

Distance of Yed Prior from the Sun and relative movement

Yed Prior is distant 170.15 light years from the Sun and it is moving towards the Sun at the speed of 20 kilometers per second.

52.19 pc
170.15 ly
-20 km/s
-0.044 arcsec/year
-0.143 arcsec/year

Spectral properties of Yed Prior

Yed Prior belongs to spectral class M0 and has a luminosity class of III corresponding to a hypergiant star.


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

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

Yed Prior star system properties

Yed Prior 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 Yed Prior double sysyem:

65.5 arcsec

Alternative designations of Yed Prior

Yed Prior
δ Ophiuchi
(delta Ophiuchi)