Constellation, Compass
Circinus
The pair of compasses, a drawing tool for circles. Nicolas-Louis de Lacaille placed it in the southern sky in the 1750s as part of a set of draughtsman’s instruments.
From New York the constellation Circinus never rises above the horizon: it belongs to the other hemisphere’s sky.
From New York the constellation Circinus never rises above the horizon: it belongs to the other hemisphere’s sky.
In the 3D sky
The sky over New York turned towards Circinus. Drag to look around.
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Evening visibility over the year
Height of the constellation’s centre above the horizon at 10 pm local time on the 15th of each month, from New York. Above about 30° it is well placed.
Name and history
Circinus has no myth. The French astronomer Nicolas-Louis de Lacaille introduced it on his chart of the southern sky as le Compas, the pair of compasses that geometers, draughtsmen and navigators used for drawing circles and measuring distances. He gave it its Latin name, Circinus, in 1763. It sits next to Norma, the set square, and Triangulum Australe, an older figure that Lacaille saw as a surveyor’s level, so the three together form a set of drawing and measuring tools.
Lacaille fitted his new figures into the gaps between the old ones. Here there was hardly any gap, so the compasses are squeezed, folded, between the forefeet of the Centaur and the Southern Triangle. Like most of Lacaille’s figures, it honours the practical tools of science rather than any hero or god.
Sources: Ian Ridpath, Star Tales: Circinus
Brightest stars
| Star | Designation | Magnitude | Distance |
|---|---|---|---|
| Xami | α Cir | 3.18 | 54 light-years |
| β Cir | β Cir | 4.07 | 100 light-years |
| γ Cir | γ Cir | 4.48 | 449 light-years |
| ε Cir | ε Cir | 4.85 | 408 light-years |
Facts
| Area | about 94 square degrees (85 of 88) |
|---|---|
| IAU abbreviation | Cir |
| Sky | Southern sky |
| Origin | First shown on Lacaille’s planisphere of the southern sky, from his 1751–52 observations at the Cape of Good Hope |
| Stars brighter than magnitude 5 | 4 |
| Centre (J2000) | 15.2 h, -62° |
Deep-sky objects
Galaxies, clusters and nebulae brighter than magnitude 9, from the OpenNGC catalogue. Most need binoculars or a telescope and a dark sky.
| Object | Type | Magnitude |
|---|---|---|
| NGC5823 | Open cluster | 7.9 |
Boundaries: International Astronomical Union, via Astronomy Engine. Areas are computed from the boundaries by sampling (within about one percent). Names and lines: Stellarium. Stars: HYG Database. Deep-sky objects: OpenNGC. Calculated with Astronomy Engine, an open-source library verified against the US Naval Observatory and NASA JPL. Data sources
How to use this page
Choose your place and a night at the top. The answer and the 3D view show where the constellation is, when it is highest and whether it rises at all from where you are. The chart shows its stars and lines, and the tables list its brightest stars and the deep-sky objects inside it.
Frequently asked questions
When is a constellation best seen?
When it is highest in a dark sky, which the page gives for the night you pick. Each constellation is best placed in a particular season, because the stars rise about four minutes earlier every night.
Why can I not see a constellation from my place?
Constellations far south of the celestial equator never rise from northern places, and those far north never rise from southern ones. The page says when this is the case.
What are the constellation boundaries?
The International Astronomical Union divides the sky into 88 areas with official boundaries. The stick figures are only a drawing aid, the boundaries say which constellation a point in the sky belongs to.
Related guides
- How to learn the constellationsStart with one bright pattern you cannot miss, use it as a signpost to its neighbours, and come back a month later: the sky will have turned, and you will know a little more of it.
- Altitude and azimuth: finding things in the skyTwo angles tell you exactly where to look: which direction, and how high.
- Light pollution and dark skies: the Bortle scaleFrom a city centre you can count a few dozen stars. From a truly dark site you can count a few thousand, with the Milky Way bright enough to cast a shadow. The Bortle scale puts a number on the difference.
- Binoculars for stargazing: what to buy and what to look atA pair of 7x50 or 10x50 binoculars shows the craters of the Moon, the moons of Jupiter, dozens of star clusters and the Andromeda Galaxy, for a fraction of the cost of a telescope.