Chisel · pronounced Caelum. Caelum, meaning “Chisel,” is an official IAU constellation centred near right ascension 4.9 hours and declination -42°. Its observing character is defined by the named stars and targets below. Lacaille introduced Caelum Sculptoris, the engraver’s chisel, after mapping the southern sky from the Cape of Good Hope. The IAU shortened the name to Caelum. Like several Lacaille figures, it celebrates a practical scientific or artistic instrument rather than mythology. The line figure is only a guide: the IAU boundary is the scientifically meaningful region, while historical and cultural interpretations require their own context.
About Caelum
Caelum is one of the 88 constellations recognized by the International Astronomical Union. Its standard three-letter abbreviation is Cae, and astronomers use the genitive form Caeli when naming stars associated with it. The constellation's reference position lies around right ascension 4.9 hours and declination -42 degrees.
Its location places it in the southern sky. For a typical mid-latitude observer, this part of the celestial sphere is especially well placed during autumn evenings. Exact visibility depends on latitude, local horizon, date and time.
History and mythology of Caelum
Origins and cultural history
Lacaille introduced Caelum Sculptoris, the engraver’s chisel, after mapping the southern sky from the Cape of Good Hope. The IAU shortened the name to Caelum. Like several Lacaille figures, it celebrates a practical scientific or artistic instrument rather than mythology.
From figure to official region
The IAU retained Chisel as one of 88 official constellations in 1922; Eugène Delporte’s boundaries later turned the traditional figure into an exact cataloguing region.
How to find Caelum
- Find bright Rigel in Orion and Achernar in Eridanus.
- Caelum lies in the faint southern area between Columba and Eridanus.
- Use binoculars to match Alpha, Beta and Gamma¹ Caeli; no obvious naked-eye shape dominates.
- Observe in December–January from southern or tropical latitudes; its galaxies require aperture and dark skies.
Bright stars in Caelum
Alpha Caeli
Notable star- Magnitude
- 4.45
- Distance
- about 66 light-years
Yellow-white dwarf and spectroscopic binary, brightest in Caelum.
Gamma¹ Caeli
Notable star- Magnitude
- 4.55
- Distance
- about 185 light-years
Orange giant in a wide optical grouping.
Beta Caeli
Notable star- Magnitude
- 5.04
- Distance
- about 94 light-years
Yellow-white dwarf with an infrared excess.
Deep-sky objects in Caelum
NGC 1679
Small southern spiral with patchy star formation.
NGC 1571
Faint galaxy for larger amateur telescopes.
HE 0450−2958
Unusual luminous quasar studied because its host galaxy was initially difficult to detect.
NGC 1595
Faint barred spiral in the Caelum galaxy field.
Interesting facts about Caelum
- Caelum’s traditional name refers to chisel, while its official IAU boundary defines a precise region of the sky.
- Alpha Caeli, at magnitude 4.45, is a key star in Caelum. Yellow-white dwarf and spectroscopic binary, brightest in Caelum.
- NGC 1679 is a notable barred spiral galaxy in Caelum. Small southern spiral with patchy star formation.
- NGC 1571, a lenticular galaxy, is another observing target within the constellation.
- Lacaille introduced Caelum Sculptoris, the engraver’s chisel, after mapping the southern sky from the Cape of Good Hope.