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Constellation in the southern celestial hemisphere
the cargo ship
Due to its small size and location away from the plane of the Milky Way, Caelum is a rather barren constellation, with few objects of interest. The constellation's brightest star, Alpha Caeli, is only of magnitude 4.45, and only one other star, (Gamma) γ1 Caeli, is brighter than magnitude 5 Other notable objects in Caelum are RR Caeli, a binary star with one known planet approximately away; X Caeli, a Delta Scuti variable that forms an optical double with γ1 Caeli; and HE0450 2958, a Seyfert galaxy that at first appeared as just a jet, with no host galaxy visible.

Caelum was incepted as one of fourteen southern constellations in the 18th century by Nicolas Louis de Lacaille, a French astronomer and celebrated of the Age of Enlightenment. It retains its name Burin among French speakers, latinized in his catalogue of 1763 as Caelum Sculptoris (“Engraver's Chisel”). Francis Baily shortened this name to Caelum, as suggested by John Herschel. In Lacaille's original chart, it was shown as a pair of engraver's tools: a standard burin and more specific shape forming échoppe tied by a ribbon, but came to be ascribed a simple chisel.

Caelum is bordered by Dorado and Pictor to the south, Horologium and Eridanus to the east, Lepus to the north, and Columba to the west. Covering only 125 square degrees, it ranks 81st of the 88 modern constellations in size. Its main asterism consists of four stars, and twenty stars in total are brighter than magnitude 6.5 The International Astronomical Union (IAU) adopted the three letter abbreviation “Cae” for the constellation in 1922. Its main stars are visible in favourable conditions and with a clear southern horizon, for part of the year as far as about the 41st parallel northefn|1=While parts technically reach the horizon to observers between 41°N and 62°N, stars within a few degrees of the horizon are to all intents and purposes unobservable. Caelum is too far south for any of its stars to bear Flamsteed designations. The brightest star, (Alpha) α Caeli, is a double star, containing an F type main sequence star of magnitude 4.45 and a red dwarf of magnitude 12.5 , from Earth. (Beta) β Caeli, another F type star of magnitude 5.05 , is further away, being located from Earth. Unlike α, β Caeli is a subgiant star, slightly evolved from the main sequence. (Delta) δ Caeli, also of magnitude 5.05 , is a B type subgiant and is much farther from Earth, at
(Gamma) γ1Caeli is a double star with a red giant primary of magnitude 4.58 and a secondary of magnitude 8.1 The primary is from Earth. The two components are difficult to resolve with small amateur telescopes because of their difference in visual magnitude and their close separation. This star system forms an optical double with the unrelated X Caeli (previously named γ2Caeli), a Delta Scuti variable located from Earth. These are a class of short period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study astroseismology. X Caeli itself is also a binary star, specifically a contact binary, meaning that the stars are so close that they share envelopes. The only other variable star in Caelum visible to the naked eye is RV Caeli, a pulsating red giant of spectral type M1III, which varies between magnitudes 6.44 and 6.56
Three other stars in Caelum are still occasionally referred to by their Bayer designations, although they are only on the edge of naked eye visibility. (Nu) ν Caeli is another double star, containing a white giant of magnitude 6.07 and a star of magnitude 10.66, with unknown spectral type. The system is approximately away. at magnitude 6.24, is much redder and farther away, being a red giant around from Earth. (Zeta) ζ Caeli is even fainter, being only of magnitude 6.36 This star, located away, is a K type subgiant of spectral type K1. The other twelve naked eye stars in Caelum are not referred to by Bode's Bayer designations anymore, including RV Caeli. One of the nearest stars in Caelum is the eclipsing binary star RR Caeli, at a distance of Despite its closeness to the Earth, the system's apparent magnitude is only 14.40 due to the faintness of its components, and thus it cannot be easily seen with amateur equipment. In 2012, the system was found to contain a giant planet, and there is evidence for a second substellar body. The system is a post common envelope binary and is losing angular momentum over time, which will eventually cause mass transfer from the red dwarf to the white dwarf. In approximately 9–20 billion years, this will cause the system to become a cataclysmic variable.

Due to its small size and location away from the plane of the Milky Way, Caelum is rather devoid of deep sky objects, and contains no Messier objects. The only deep sky object in Caelum to receive much attention is HE0450 2958, an unusual Seyfert galaxy. Originally, the jet's host galaxy proved elusive to find, and this jet appeared to be emanating from nothing. Although it has been suggested that the object is an ejected supermassive black hole, the host is now agreed to be a small galaxy that is difficult to see due to light from the jet and a nearby starburst galaxy. The 13th magnitude planetary nebula PN G243 37.1 is also in the eastern regions of the constellation. It is one of only a few planetary nebulae found in the galactic halo, being 20000 light years below the Milky Way's 1000 light year thick disk. Galaxies NGC 1595, NGC 1598, and the Carafe galaxy are known as the Carafe group. The Carafe galaxy is a Seyfert galaxy with ring. Its location is 4:28 / 47°54' (2000.0).