σ Ophiuchi (sigma Ophiuchi)

Altitude: -32.1° Azimuth: 337.4° Direction: North-North-West

σ Ophiuchi is a variable bright giant star in the constellation of Ophiuchus.

σ Ophiuchi visual magnitude is 4.34. Because of its moderate brightness, σ Ophiuchi 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 σ Ophiuchi:

Color of σ Ophiuchi ⬤

Magnitude of σ Ophiuchi 4.34

Class Bright giant

VISIBILITY RIGHT NOW

σ Ophiuchi (sigma Ophiuchi) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -32.1°
Azimuth: 337.4°
Direction: North-North-West

Celestial coordinates and finder chart of σ Ophiuchi

σ Ophiuchi 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 σ Ophiuchi are provided in the following table:

Right Ascension J2000 17h 26m 30s

Declination J2000 +04° 08’ 25”

Galactic Longitude 26.77°

Galactic Latitude 20.75°

Constellation Ophiuchus

The simplified sky map below shows the position of σ Ophiuchi in the sky:

Finder chart σ Ophiuchi (sigma Ophiuchi) star

Simplified finder chart for σ Ophiuchi (sigma Ophiuchi).

Visibility of σ Ophiuchi 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 σ Ophiuchi (sigma 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: 85.9° RISE 6:31

Max altitude: 42.7° TRANSIT 12:49

Azimuth: 274.1° SET 19:08

Digitized Sky Survey image of σ Ophiuchi

The image below is a photograph of σ Ophiuchi 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 σ Ophiuchi is 0.004 arcsec per year in Right Ascension and 0.007 arcsec per year in Declination and the associated displacement for the next 100000 years is represented with the red arrow.

Image of σ Ophiuchi (sigma Ophiuchi) star

DSS2 image of σ Ophiuchi. The red arrow shows the motion of σ Ophiuchi during the next 100000 years (6.67 arcmin in Right Ascension and 11.67 arcmin in declination);

Distance of σ Ophiuchi from the Sun and relative movement

σ Ophiuchi is distant 1,172.66 light years from the Sun and it is moving towards the Sun at the speed of 27 kilometers per second.

Distance (parsec) 359.71 pc

Distance (light year) 1,172.66 ly

Heliocentric radial velocity -27 km/s

Proper Motion RA 0.004 arcsec/year

Proper Motion Dec 0.007 arcsec/year

Spectral properties of σ Ophiuchi

σ Ophiuchi belongs to spectral class K2 and has a luminosity class of II corresponding to a bright giant star.

Absolute magnitude -3.44

Spectral Type K2II

Color Index (B-V) 1.5

Temperature of σ Ophiuchi 3794K

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

H-R diagram showing the position of σ Ophiuchi. Attribution: Richard Powell / CC BY-SA

Alternative designations of σ Ophiuchi

Bayer designation σ Ophiuchi
(sigma Ophiuchi)

Flamsteed designation 49 Ophiuchi

Henry Draper Catalogue HD157999

SAO Catalogue SAO122387

Hipparcos Catalogue HIP85355

Durchmusterung Catalogue BD+04 3422

FK5 Catalogue 1459

General Catalogue of Variable Stars 8664

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In Evidence

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