τ Ophiuchi (tau Ophiuchi)

Below the horizon. Rise: 19:42 | Tran: 1:02 | Set: 6:19

Alt: -8.69° Az: 92.24° Direction: South

τ Ophiuchi is a variable and multiple main-sequence star of spectral class F2 in the constellation of Ophiuchus.

τ Ophiuchi visual magnitude is 5.24. Because of its faintness, τ Ophiuchi is visible to the naked eye only from locations with very dark skies, while it is not visible at all from skies affected by light pollution.

DSS2 image of τ Ophiuchi. The red arrow shows the motion of τ Ophiuchi during the next 10000 years (4.67 arcmin in Right Ascension and -6.17 arcmin in declination);

Celestial Coordinates

Apparent

Right Ascension 18h 04m 28s

Declination -08° 10’ 41”

Hour Angle 17h 45m 12s

Sidereal Time 11h 49m 40s

J2000

Right Ascension 18h 03m 04s

Declination -08° 10’ 50”

Galactic Coordinates

Galactic Longitude 20.06°

Galactic Latitude 6.87°

Finder Chart

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Finder chart for τ Ophiuchi (tau Ophiuchi).

Magnitude, Color, Spectral Class

Color ⬤

Magnitude 5.24

Class Main-sequence

Absolute magnitude 1.66

Spectral Type F2V

Color Index (B-V) 0.38

Temperature 6989K

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

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

Star System Properties

τ Ophiuchi 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 τ Ophiuchi double sysyem:

Main star magnitude 5.24

Secondary star magnitude 5.94

Magnitude difference 0.7

Separation 1.9 arcsec

Distance, Radial Speed, Proper Motion

τ Ophiuchi is distant 169.61 light years from the Sun and it is moving towards the Sun at the speed of 40 kilometers per second.

Distance (parsec) 52.03

Distance (light year) 169.61

Radial Speed -40 km/s

Proper Motion RA 0.028 arcsec/y

Proper Motion Dec -0.037"/y

Alternative Designations

Bayer designation τ Ophiuchi
(tau Ophiuchi)

Flamsteed designation 69 Ophiuchi

Henry Draper Catalogue HD164765

SAO Catalogue SAO142050

Durchmusterung Catalogue BD-08 4549

Gliese Catalogue Gl 700.1A

General Catalogue of Variable Stars 10073

Aitken Double Star Catalogue ADS11005

Visibility from Your Location

Today's τ Ophiuchi (tau Ophiuchi) rise, transit and set times from Greenwich, UK are the following (all times relative to the local timezone Europe/London):

Azimuth: 98.2° RISE 19:42

Max altitude: 30.3° TRANSIT 1:02

Azimuth: 261.8° SET 6:19

Set Location

Other stars in Ophiuchus