When is the best time to observe Etamin?

Etamin is best observed from May through July, with peak visibility during June when it transits around midnight in the Northern Hemisphere.

Where is Etamin located in the sky?

Etamin lies in the constellation Draco at right ascension 17h 57m and declination +51° 29′.

What telescope do I need to split Etamin?

Splitting Etamin requires an aperture of roughly 60 mm or larger — the components are separated by about 142.3″ at magnitudes near 2.2. The companion is about 9.0 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Etamin — Double Star in Draco

HIP 87833; Gamma Draconis; 33 Draconis

DoubleStar Draco (Dra) Visible

Star Map + List + Plan

About Etamin

Description

Eltanin (also spelled Etamin) is an orange giant of spectral type K5III at magnitude 2.23, the brightest star in Draco. Located about 154 light-years from Earth, it has a luminosity of roughly 471 times solar. Despite its Gamma designation, it is brighter than Alpha Draconis.

Observing Tips

Eltanin marks the head of Draco, forming part of a small quadrilateral with Beta, Xi, and Nu Draconis. It is visible year-round from mid-northern latitudes as part of the circumpolar constellation. Its orange color is apparent in binoculars. Look for the Dragon's head between Vega and the Keystone of Hercules. Best placed high overhead during summer evenings.

History

The name Eltanin comes from the Arabic 'al-tinnin,' meaning 'the great serpent.' In 1728, James Bradley attempted to measure the parallax of Eltanin and instead discovered the aberration of light — the apparent shift in star positions caused by Earth's orbital velocity. This was the first direct evidence that Earth orbits the Sun.

Fun Facts

Bradley's discovery of stellar aberration using Eltanin was one of the most important observations in the history of astronomy, providing the first observational proof of Earth's orbital motion. In about 1.5 million years, Eltanin will pass within 28 light-years of Earth and become the brightest star in the sky.

Observe

1Physical Properties

Magnitude 2.23

Spectral Type K5III

Star Color Red (B-V 1.52)

Distance 154 ly

2Position & Identifiers

RA 17h 56m 36.4s

Dec +51° 29' 20.0"

Constellation Draco (Dra)

HR 6705

HIP 87833

HD 164058

Bayer Gamma

Flamsteed 33 Dra

Double Cat 10923

SIMBAD Wikipedia

3How easy to split?

Primary 2.2 mag Companion 11.2 mag Separation 142.3″

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Hard+	Hard	V. hard+
150 mm Newton 150mm Newt.	Medium+	Medium	Hard+
Celestron C8 (203 mm SCT) C8 203mm	Easy	Medium+	Medium

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

4Visibility

Set a location in User Settings to see visibility data.

Best season May – Jul (peak: Jun)

5Multiple Star System Septuple

Components 7 (septuple)

Component IDs AG

Separation 142.3″

Companion Mag 11.2

Position Angle 26°

Star Colors A: Red

Discoverer BU 633

Separation over time

Measured 1898 → 2023 (125 y)

Separation drift 139.2" → 142.3" (+3.10")

Rate +0.0248" / y

PA drift 28° → 26° (-2°, -0.016°/y)

Apparent motion is significant on a human timescale — worth revisiting in a decade.

Measured from the WDS observational archive. No orbital solution has been derived — most likely the period is too long to fit an orbit to the available measurement arc.