Constellation, Clock
Horologium
The pendulum clock, one of the precision instruments that Nicolas-Louis de Lacaille set among the southern stars in the 1750s.
From New York on October 13, 2026, the centre of Horologium rises at 2:50 AM, is highest at 3:21 AM (0° above the horizon in the S) and sets at 3:53 AM.
In the 3D sky
The sky over New York turned towards Horologium. 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
Horologium has no myth. Nicolas-Louis de Lacaille introduced it after mapping the southern sky from the Cape of Good Hope in 1751 and 1752. He wrote that it showed a pendulum clock beating seconds, of the kind he used to time his observations. On his chart of 1756 its French name was l’Horloge, and he drew it with a full dial and a seconds hand. It sits next to Reticulum, the reticle in his telescope eyepiece, which he used with the clock to time the passage of stars.
On the second edition of his chart, in 1763, the name became Horologium. Lacaille drew a simple clock of the type invented by Christiaan Huygens, with its brightest star on one of the driving weights. Later the German astronomer Johann Bode drew a more advanced pendulum, with that star as the bob.
Sources: Ian Ridpath, Star Tales: Horologium
Brightest stars
| Star | Designation | Magnitude | Distance |
|---|---|---|---|
| α Hor | α Hor | 3.85 | 115 light-years |
| δ Hor | δ Hor | 4.93 | 179 light-years |
| β Hor | β Hor | 4.98 | 295 light-years |
Facts
| Area | about 250 square degrees (58 of 88) |
|---|---|
| IAU abbreviation | Hor |
| 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 | 3 |
| Centre (J2000) | 3.9 h, -50° |
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 |
|---|---|---|
| NGC1261 | Globular cluster | 8.6 |
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
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- 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.