Circinus
What is Circinus?
Constellations· Southern autumn · a narrow triangle beside Alpha Centauri. Lacaille's tiny tribute to the drafting compass, a thin triangle beside Alpha Centauri. Hidden in this direction are the nearby active Circinus Galaxy and the X-ray binary Circinus X-1.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Circinus is in your sky right now: https://nowsky.org/solar/sky?sel=con:Circinus — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Alpha Circini | 3.2 |
The 1 brightest of the 2 stars used in the figure (1 lines). Lower magnitude means brighter.
Constellation basics
| Season | May–Jun evenings; never visible from Korea |
|---|---|
| Brightest star | α Circini, mag 3.2 |
| How to find | a thin, elongated triangle just south of Alpha Centauri |
| Area rank | 85th of 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Circinus?
- May–Jun evenings; never visible from Korea.
- How do I find Circinus?
- a thin, elongated triangle just south of Alpha Centauri.
- What is the brightest star in Circinus?
- Alpha Circini, magnitude 3.2.
- Where is Circinus in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
The Hand of God — the X-ray nebula of a pulsar in Circinus
Seventeen thousand light-years away in the direction of Circinus is the pulsar PSR B1509-58, a young neutron star 1,700 years old spinning seven times a second. In a Chandra X-ray image of 2009 the wind of particles from the pulsar formed a nebula shaped like a hand with fingers spread, its fingertips touching a neighbouring gas cloud that glows red, and the picture earned the nickname the Hand of God.
The nebula is 150 light-years across, a structure made as the pulsar's magnetic field flings electrons near light speed out along its poles. Whether the hand is a real three-dimensional shape or an accident of projection was not fully resolved even by NuSTAR's high-energy observations. Behind the thin triangle beside Alpha Centauri, a dead star draws a picture of an open hand.
The constellation in depth
Circinus is one of the scientific-instrument constellations Lacaille drew in the 1750s, honouring the drafting compass used to draw circles, and placed to pair with the neighbouring Norma, the set square. It is the fourth-smallest of the 88 constellations, and sitting right beside Alpha Centauri it is easily lost in that star's glare. Beta and gamma Circini, both of the fourth magnitude, complete the narrow triangle.
Alpha Circini, the brightest star at magnitude 3.2 and about 54 light-years away, is the prototype of the rapidly oscillating Ap stars studied in asteroseismology. Behind the dust of the Milky Way lies the Circinus Galaxy, a nearby Seyfert galaxy about 13 million light-years away, and Circinus X-1, an X-ray binary sitting inside a supernova remnant. Both are best seen in the infrared and X-rays rather than visible light.
At declinations of −55° to −70° it cannot be seen from Korea. From the southern hemisphere, wait for May or June evenings when Alpha Centauri and Hadar are high and look for the thin triangle just south of them. In the Sky view, set Cape Town or Sydney on a May evening and zoom in beside Alpha Centauri. The constellation lines help separate it from the glare of Alpha Centauri.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.