Constellation, Telescope
Telescopium
A long aerial telescope hung from a mast, one of the instruments Nicolas Louis de Lacaille set in the southern sky. Later astronomers cut it down to a small rectangle south of Sagittarius.
From New York on October 13, 2026, the centre of Telescopium rises at 5:27 PM, is highest at 6:21 PM (1° above the horizon in the S) and sets at 7:14 PM.
In the 3D sky
The sky over New York turned towards Telescopium. 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
Nicolas Louis de Lacaille introduced this figure after mapping the southern sky from the Cape of Good Hope in 1751–52. He called it le Telescope in 1756 and Telescopium in 1763. It shows an aerial telescope, a very long refractor hung from a pole, of the kind J. D. Cassini used at the Paris Observatory. Telescopes of that time were made extremely long to reduce the false colours produced by their simple lenses. There is no myth here, only a tribute to the tool of the astronomer.
Lacaille drew his telescope reaching far north between Sagittarius and Scorpius. Later astronomers cut it back. Francis Baily handed some of its stars to neighbouring constellations in 1845, and Benjamin Gould first showed its present rectangle in 1877. As a result, stars that once marked the pulley and the lens now belong to Sagittarius, Scorpius and Ophiuchus.
Sources: Ian Ridpath, Star Tales: Telescopium
Brightest stars
| Star | Designation | Magnitude | Distance |
|---|---|---|---|
| α Tel | α Tel | 3.49 | 278 light-years |
| ζ Tel | ζ Tel | 4.10 | 126 light-years |
| ε Tel | ε Tel | 4.52 | 418 light-years |
| λ Tel | λ Tel | 4.85 | 612 light-years |
| ι Tel | ι Tel | 4.88 | 371 light-years |
| δ1 Tel | δ1 Tel | 4.92 | 708 light-years |
| ξ Tel | ξ Tel | 4.93 | 1,080 light-years |
Facts
| Area | about 253 square degrees (57 of 88) |
|---|---|
| IAU abbreviation | Tel |
| Sky | Southern sky |
| Origin | First shown as le Telescope on Lacaille’s planisphere of 1756, from his observations at the Cape in 1751–52 |
| Stars brighter than magnitude 5 | 7 |
| Centre (J2000) | 18.9 h, -49° |
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 |
|---|---|---|
| NGC6584 | Globular cluster | 8.2 |
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.