We use cookies to deliver essential features and to measure their performance. By using this site you accept our Privacy Policies.
A Complete Guide to the Solar System and the Night Sky
Donate now and help us to keep this site free and ad-free!
public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 7:52  
clear_day Transit: 11:51  
SunsetSet: 15:49 south
wb_twilight Civil TwilightWhat's Visible Now?
All Constellations » Aquarius » 

τ1 Aquarii (tau1 Aquarii)

Altitude: -46.4°   Azimuth: 41.2°   Direction: North-East

τ1 Aquarii is a multiple hypergiant star in the constellation of Aquarius.

τ1 Aquarii visual magnitude is 5.66. Because of its reltive faintness, τ1 Aquarii should be visible only from locations with dark skyes, while it is not visible at all from skyes affected by light pollution.

The table below summarizes the key facts about τ1 Aquarii:


τ1 Aquarii (tau1 Aquarii) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -46.4°
Azimuth: 41.2°
Direction: North-East

Celestial coordinates and finder chart of τ1 Aquarii

τ1 Aquarii 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 τ1 Aquarii are provided in the following table:

22h 47m 42s
-14° 03’ 23”

The simplified sky map below shows the position of τ1 Aquarii in the sky:

Finder chart τ1 Aquarii (tau1 Aquarii) star
Simplified finder chart for τ1 Aquarii (tau1 Aquarii).

Visibility of τ1 Aquarii 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 τ1 Aquarii (tau1 Aquarii) 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: 104.1°
Max altitude: 24.5°
Azimuth: 255.9°

Digitized Sky Survey image of τ1 Aquarii

The image below is a photograph of τ1 Aquarii 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 τ1 Aquarii is 0.032 arcsec per year in Right Ascension and -0.009 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of τ1 Aquarii (tau1 Aquarii) star
DSS2 image of τ1 Aquarii. The red arrow shows the motion of τ1 Aquarii during the next 10000 years (5.33 arcmin in Right Ascension and -1.50 arcmin in declination);

Distance of τ1 Aquarii from the Sun and relative movement

τ1 Aquarii is distant 259.76 light years from the Sun and it is moving far from the Sun at the speed of 15 kilometers per second.

79.68 pc
259.76 ly
15 km/s
0.032 arcsec/year
-0.009 arcsec/year

Spectral properties of τ1 Aquarii

τ1 Aquarii 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 τ1 Aquarii is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of τ1 Aquarii. Attribution: Richard Powell / CC BY-SA

τ1 Aquarii star system properties

τ1 Aquarii is a visual double star which can be observed with binoculars or small telescopes. The table below shows key information about the τ1 Aquarii double sysyem:

23.7 arcsec

Alternative designations of τ1 Aquarii

τ1 Aquarii
(tau1 Aquarii)