η Cygni (eta Cygni)

Altitude: 54.0° Azimuth: 99.1° Direction: East

η Cygni is a variable and multiple hypergiant star in the constellation of Cygnus.

η Cygni visual magnitude is 3.89. Because of its moderate brightness, η Cygni 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 η Cygni:

Color of η Cygni ⬤

Magnitude of η Cygni 3.89

Class Hypergiant

VISIBILITY RIGHT NOW

η Cygni (eta Cygni) is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 54.0°
Azimuth: 99.1°
Direction: East

Celestial coordinates and finder chart of η Cygni

η Cygni is situated north of the celestial equator, as such, it is more easily visible from the northern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of η Cygni are provided in the following table:

Right Ascension J2000 19h 56m 18s

Declination J2000 +35° 04’ 59”

Galactic Longitude 71.02°

Galactic Latitude 3.36°

Constellation Cygnus

The simplified sky map below shows the position of η Cygni in the sky:

Simplified finder chart for η Cygni (eta Cygni).

Visibility of η Cygni 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 η Cygni (eta Cygni) 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: 54.9° RISE 5:07

Max altitude: 73.6° TRANSIT 15:11

Azimuth: 305.1° SET 1:19

Digitized Sky Survey image of η Cygni

The image below is a photograph of η Cygni 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 η Cygni is -0.032 arcsec per year in Right Ascension and -0.027 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

DSS2 image of η Cygni. The red arrow shows the motion of η Cygni during the next 10000 years (-5.33 arcmin in Right Ascension and -4.50 arcmin in declination);

Distance of η Cygni from the Sun and relative movement

η Cygni is distant 139.32 light years from the Sun and it is moving towards the Sun at the speed of 27 kilometers per second.

Distance (parsec) 42.74 pc

Distance (light year) 139.32 ly

Heliocentric radial velocity -27 km/s

Proper Motion RA -0.032 arcsec/year

Proper Motion Dec -0.027 arcsec/year

Spectral properties of η Cygni

η Cygni belongs to spectral class K0 and has a luminosity class of III corresponding to a hypergiant star.

Absolute magnitude 0.74

Spectral Type K0III

Color Index (B-V) 1.02

Temperature of η Cygni 4695K

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

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

η Cygni star system properties

η Cygni 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 η Cygni double sysyem:

Main star magnitude 3.89

Secondary star magnitude 11.59

Magnitude difference 7.7

Separation 46 arcsec

Alternative designations of η Cygni

Bayer designation η Cygni
(eta Cygni)

Flamsteed designation 21 Cygni

Henry Draper Catalogue HD188947

SAO Catalogue SAO69116

Hipparcos Catalogue HIP98110

Durchmusterung Catalogue BD+34 3798

FK5 Catalogue 1521

General Catalogue of Variable Stars 12586

Aitken Double Star Catalogue ADS13149

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