Sextans
What is Sextans?
Constellations· Spring evenings (N) · on the celestial equator south of Regulus. Hevelius placed his own sextant — the instrument he used to measure star positions — in the sky here, south of Regulus on the celestial equator. Every star is fainter than 4th magnitude. The edge-on lenticular NGC 3115, the Spindle Galaxy, is its showpiece. Zoom in south of Regulus in the Sky view.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Sextans is in your sky right now: https://nowsky.org/solar/sky?sel=con:Sextans — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Alpha Sextantis | 4.5 |
The 1 brightest of the 3 stars used in the figure (2 lines). Lower magnitude means brighter.
Deep-sky objects near this constellation
Constellation basics
| Season | spring evenings (N) |
|---|---|
| Brightest star | Alpha Sextantis (4.5) |
| How to find | about 12 degrees south of Regulus |
| Area rank | 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Sextans?
- spring evenings (N).
- How do I find Sextans?
- about 12 degrees south of Regulus.
- What is the brightest star in Sextans?
- Alpha Sextantis, magnitude 4.5.
- Where is Sextans 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 empty window in Sextans — the COSMOS field
Sextans contains a patch of sky free of both the Milky Way's dust and bright stars. Since the mid-2000s the world's major telescopes — Hubble, Spitzer, Chandra, XMM, Subaru, the VLA and others — have observed this region, nine full moons in area, together in a survey called COSMOS. More than two million galaxies have been recorded, a deep look in one direction through ten billion years of cosmic history.
The spot was chosen because it can be seen from both hemispheres and almost nothing stands in front of it. From the COSMOS data maps were drawn of how the large-scale structure of galaxies grew from epoch to epoch and where dark matter clumped, and Webb turned to the same region in 2023. A constellation whose brightest star is 4.5th magnitude is therefore among those most often named in modern cosmology.
The constellation in depth
Sextans was created by Hevelius in 1687 to commemorate the great sextant he used from 1658 until fire destroyed his observatory in 1679. Even after telescopes spread he insisted on naked-eye sighting instruments, and his measurements were the most precise of the age. It is a modern constellation honouring a tool rather than a myth.
With Alpha at only magnitude 4.5, the figure itself is inconspicuous. Instead, NGC 3115 — the Spindle Galaxy, 32 million light-years away — is a bright edge-on lenticular visible in small telescopes and hosts a black hole of about two billion solar masses. Cosmos Redshift 7, a galaxy found in 2015 showing traces of the universe's first generation of stars, lies in this direction, as do the Local Group dwarfs Sextans A and B.
On March–May evenings find Regulus in Leo in the south, then look about 12 degrees straight below it. Its stars are too faint for city skies, so enable constellation lines in the Sky view to learn the region. Sitting on the celestial equator, it is visible from both hemispheres.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.