When is the best time to observe Alnitak?

Alnitak is best observed from November through January, with peak visibility during December when it transits around midnight in the Northern Hemisphere.

Where is Alnitak located in the sky?

Alnitak lies in the constellation Orion at right ascension 05h 41m and declination -01° 57′.

What telescope do I need to split Alnitak?

Splitting Alnitak requires an aperture of roughly 100 mm or larger — the components are separated by about 2.4″ at magnitudes near 2.0. Larger apertures and steady seeing help resolve the pair cleanly.

Alnitak — Double Star in Orion

HIP 26727; Zeta Orionis; 50 Orionis

Observable Double Star Good (58/100)

Sep: 2.4", Companion: mag 3.7

Magnitude 2.0^m DoubleStar Orion (Ori) Visible

Star Map + List + Plan

About Alnitak

Description

Alnitak is the easternmost star of Orion's Belt at magnitude 2.05, a hot blue supergiant of spectral type O9.7Ib. Located about 1,200 light-years from Earth, it has a luminosity of roughly 250,000 times solar — one of the most luminous stars in the Orion region. Alnitak is a triple star system; the close companion is resolvable in moderate telescopes.

Observing Tips

Alnitak is the left (eastern) star of Orion's Belt. Just south of Alnitak lies the famous Horsehead Nebula (B33) and the bright Flame Nebula (NGC 2024) — both illuminated by Alnitak's intense radiation. The Belt stars are among the easiest patterns to identify in the entire sky. Best observed December through March.

History

The name Alnitak comes from the Arabic 'al-nitaq,' meaning 'the girdle' or 'the belt.' Together with Alnilam and Mintaka, the three Belt stars have been recognized and named across virtually every culture. They were 'the Three Kings,' 'the Three Marys,' and 'the String of Pearls' in various traditions.

Fun Facts

Alnitak is responsible for illuminating the Flame Nebula and creating the silhouette of the famous Horsehead Nebula, one of the most photographed objects in the sky. The star is so energetic that its ultraviolet light ionizes the gas clouds over a light-year away.

Observe

1Physical Properties

Magnitude 2.05

Range 1.74 - 1.77

Variable Type Variable (Unclassified)

Spectral Type O9.7Ib supergiant

Star Color Blue (B-V -0.21)

Distance 136 ly

2Position & Identifiers

RA 05h 40m 45.5s

Dec -01° 56' 34.0"

Constellation Orion (Ori)

HR 1948

HIP 26727

HD 37742

SAO 132444

Bayer Zeta

Flamsteed 50 Ori

Double Cat 4263

SIMBAD Wikipedia

3How easy to split?

Primary 2.1 mag Companion 3.7 mag Separation 2.4″

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

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 Nov – Jan (peak: Dec)

5Multiple Star System Triple

Components 3 (triple)

Component IDs AB

Separation 2.4″

Companion Mag 3.7

Companion Sp B0III

Position Angle 167°

Star Colors A: Blue B: Blue

Discoverer STF 774

Notes

AB 1.88 O9.5Ib, 4.02 B2III, 1508.6y, a = 2.728". Colors for combined light. Blended magnitude 1.76V, 18 and 6 solar | masses. B is HR 1949. C is 9v at 58", possibly physical.