✦ Ophiuchus (Oph)
✦ Ophiuchus (Oph)
Subfolder of: Fixed Stars · Constellations
| Field | Value |
|---|---|
| IAU name | Ophiuchus |
| IAU abbreviation | Oph |
| Latin genitive (used in Bayer names) | Ophiuchi |
| 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 Ophiuchus
| Star | Designation | λ J2000.0 | λ 2026.0 | V mag |
|---|---|---|---|---|
| Yed Prior | δ Ophiuchi | 2°17′ Sagittarius | 2°39′ Sagittarius | 2.75 |
| Yed Posterior | ε Ophiuchi | 3°30′ Sagittarius | 3°52′ Sagittarius | 3.23 |
| Sabik | η Ophiuchi | 17°57′ Sagittarius | 18°19′ Sagittarius | 2.42 |
| Ras Alhague | α Ophiuchi | 22°26′ Sagittarius | 22°48′ Sagittarius | 2.07 |
| Rasalhague | α Ophiuchi | 22°26′ Sagittarius | 22°48′ Sagittarius | 2.07 |
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)