Constellation, Oph
Ophiuchus: the Serpent Bearer
Ophiuchus covers 949 square degrees of sky, the 11th largest of the 88. Its brightest star is Rasalhague. It is best placed in the evening sky in July.
Show Ophiuchus in the live sky
Ophiuchus at a glance
| Fact | Value |
|---|---|
| IAU abbreviation | Oph |
| Meaning | the Serpent Bearer |
| Pronounced | OFF-ee-YOO-kus, OAF-ee-YOO-kus |
| Genitive, used in star names | Ophiuchi (for example a Bayer name such as α Ophiuchi) |
| Area | 949 square degrees, number 11 of 88 by size |
| Stars to magnitude 6 in our catalogue | 84 |
| Brightest star | Rasalhague, magnitude 2.1 |
| Best seen | Evenings in July, when it is highest at 9 pm |
| Declination range | -30° to 14° |
| Borders | Serpens, Scorpius, Hercules, Sagittarius, Aquila, Libra |
Where on Earth you can see Ophiuchus
Ophiuchus spans declinations -30° to 14°. Every part of it rises above the horizon at some moment for observers between latitudes 76°S and 60°N. Some of it can be seen from every latitude. This is geometry only: it ignores haze, hills and buildings near the horizon.
From six cities
| City | Latitude | Visibility | Middle at its highest |
|---|---|---|---|
| Pune | 18.5°N | All of it rises | 66° |
| New York | 40.7°N | All of it rises | 43° |
| London | 51.5°N | All of it rises | 33° |
| Tromsø | 69.6°N | Only part of it rises | 14° |
| Tokyo | 35.7°N | All of it rises | 48° |
| Sydney | 33.9°S | All of it rises | 62° |
Ophiuchus's named stars
These stars in Ophiuchus have names approved by the IAU Working Group on Star Names. Magnitude is brightness: a lower number is brighter, and the faintest stars seen with the naked eye on a dark night are about magnitude 6.
| Star | Designation | Magnitude | Distance (light-years) |
|---|---|---|---|
| Rasalhague | α Ophiuchi | 2.08 | 48.6 |
| Sabik | η Ophiuchi | 2.43 | 88.4 |
| Yed Prior | δ Ophiuchi | 2.73 | 170 |
| Cebalrai | β Ophiuchi | 2.76 | 81.8 |
| Yed Posterior | ε Ophiuchi | 3.23 | 110 |
| Marfik | λ Ophiuchi | 3.82 | 170 |
| Guniibuu | HR 6402 | 4.33 | 19.3 |
Distances are about, from the HYG database (Hipparcos parallax), and "not known" means the catalogue has no reliable parallax for that star.
How these facts were found
The name, meaning and boundaries are the IAU's. Area, borders and the latitude ranges are computed from those boundaries; the brightest star and the star count come from a magnitude-6 star catalogue; star names are matched to the catalogue by Hipparcos number and checked by position. The month is when Ophiuchus's middle crosses the north-south line of the sky at 9 pm local solar time. See How we know.
Sources
- IAU: The Constellations. Names, meanings, pronunciations and boundaries
- IAU Working Group on Star Names. The official names of stars
- astronomy-engine. The MIT licensed library that does the calculations, run on the page's build machine and in the app
- HYG database v4.4 (astronexus). Distances, spectral types and luminosities, licence CC BY-SA 4.0