✦ Orion (Ori)
✦ Orion (Ori)
Subfolder of: Fixed Stars · Constellations
| Field | Value |
|---|---|
| IAU name | Orion |
| IAU abbreviation | Ori |
| Latin genitive (used in Bayer names) | Orionis |
| Zodiacal constellation | No |
| Ptolemaic constellation | Yes — one of Ptolemy’s 48 (Almagest VII–VIII) |
Constellations are not the same as the tropical signs: the signs are 30° divisions measured from the March equinox, while constellations are IAU sky regions of unequal size. Precession has moved the constellations roughly one sign-width against the tropical zodiac since antiquity.
Vault stars in Orion
| Star | Designation | λ J2000.0 | λ 2026.0 | V mag |
|---|---|---|---|---|
| Rigel | β Orionis | 16°50′ Gemini | 17°11′ Gemini | 0.13 |
| Bellatrix | γ Orionis | 20°57′ Gemini | 21°18′ Gemini | 1.64 |
| Mintaka | δ Orionis | 22°22′ Gemini | 22°43′ Gemini | 2.41 |
| Alnilam | ε Orionis | 23°28′ Gemini | 23°49′ Gemini | 1.69 |
| Betelgeuse | α Orionis | 28°45′ Gemini | 29°07′ Gemini | 0.42 |
Sources
- IAU, The Constellations (88 official constellations, abbreviations): https://www.iau.org/public/themes/constellations/
- Swiss Ephemeris fixed-star catalogue
sefstars.txt(ICRS/Hipparcos-based positions, proper motions, magnitudes): https://github.com/aloistr/swisseph/blob/master/ephe/sefstars.txt — ecliptic longitudes computed for this vault with Astropy 8.0 (GeocentricMeanEcliptic, mean equinox of J2000.0 and of 2026-01-01) - Ptolemy, Almagest VII–VIII (star catalogue of 48 constellations), trans. G. J. Toomer (1984)