Caelum is a weak constellation in the southern sky that was named after Nicolas Louis de Lacaille in the 1750s and is one of the 88 modern constellations. It was once known as Caelum Sculptorium ("the engravers' chisel"), and its name means "chisel" in Latin. It is a rare word, unrelated to the far more common Latin caelum, which means "sky, heaven, atmosphere." It is the ninth smallest constellation, with a solid angle of 0.038 steradians, somewhat less than Corona Australis.
Caelum is a barren constellation with few objects of interest because of its modest size and placement away from the Milky Way's plane. The brightest star in the constellation, Alpha Caeli, is only magnitude 4.45, while only (Gamma) 1 Caeli is brighter than magnitude 5. Other notable objects in Caelum include RR Caeli, a binary star with one known planet located approximately 20.13 parsecs (65.7 ly) away; X Caeli, a Delta Scuti variable that forms an optical double with 1 Caeli; and HE0450-2958, a Seyfert galaxy that at first appeared to be nothing more than a jet with no host galaxy visible. |
History
Nicolas Louis de Lacaille, a French astronomer and proponent of the Age of Enlightenment, created Caelum as one of fourteen southern constellations in the 18th century. It is still known as Burin among French speakers, but it was Latinized as Caelum Sculptoris ("Engraver's Chisel") in his 1763 catalogue.
As recommended by John Herschel, Francis Baily abbreviated the word to Caelum. It was originally depicted as a pair of engraver's tools: a conventional burin and a more specific shape-forming échoppe connected by a ribbon in Lacaille's original chart, but it was later ascribed to a plain chisel. Caela Scalptoris – in German (die) Grabstichel ("the Engraver's Chisels") – was stated as plural with a singular owner by Johann Elert Bode, but this did not hold.
Nicolas Louis de Lacaille, a French astronomer and proponent of the Age of Enlightenment, created Caelum as one of fourteen southern constellations in the 18th century. It is still known as Burin among French speakers, but it was Latinized as Caelum Sculptoris ("Engraver's Chisel") in his 1763 catalogue.
As recommended by John Herschel, Francis Baily abbreviated the word to Caelum. It was originally depicted as a pair of engraver's tools: a conventional burin and a more specific shape-forming échoppe connected by a ribbon in Lacaille's original chart, but it was later ascribed to a plain chisel. Caela Scalptoris – in German (die) Grabstichel ("the Engraver's Chisels") – was stated as plural with a singular owner by Johann Elert Bode, but this did not hold.
Characteristics
Caelum is bordered on the south by Dorado and Pictor, on the east by Horologium and Eridanus, on the north by Lepus, and on the west by Columba. It is the smallest of the 88 contemporary constellations, with only 125 square degrees. Its major asterism has four stars, with a total of twenty stars brighter than magnitude 6.5. Belgian astronomer Eugène Delporte defined the constellation's borders as a 12-sided polygon in 1930. The right ascension coordinates of these borders in the equatorial coordinate system range from 04h 19.5m to 05h 05.1m, with declinations ranging from 27.02° to 48.74°. [2] In 1922, the International Astronomical Union (IAU) gave the constellation the three-letter acronym "Cae." (Russell 1922) |
Its primary stars are visible for part of the year as far north as the 41st parallel north in excellent conditions and with a clear southern horizon. (Few reach the horizon between 41-62 degrees N but for all intense purposes, it is unobservable)
These stars avoid being enveloped by daylight for part of every day (while above the horizon) to viewers in the Southern Hemisphere's mid- and higher latitudes. Caelum shares a midnight culmination with (to the north) Taurus, Eridanus, and Orion in December (high summer), resulting in this fact. The constellation can be seen sufficiently inset from the horizons at its rise before dawn and/or setting after twilight in the winter (such as June), as it culminates around mid-day, much above the sun. The key stars can be traced before dawn in the east in South Africa, Argentina, their sub-tropical neighbouring areas, and some of Australia in late June; near the equator, the stars lose night potential from May to June; they ill-compete with the Sun in the northern tropics and sub-tropics from late February to mid-September, with March being unfavourable as to post-sunset due to the Milky Way's light.
These stars avoid being enveloped by daylight for part of every day (while above the horizon) to viewers in the Southern Hemisphere's mid- and higher latitudes. Caelum shares a midnight culmination with (to the north) Taurus, Eridanus, and Orion in December (high summer), resulting in this fact. The constellation can be seen sufficiently inset from the horizons at its rise before dawn and/or setting after twilight in the winter (such as June), as it culminates around mid-day, much above the sun. The key stars can be traced before dawn in the east in South Africa, Argentina, their sub-tropical neighbouring areas, and some of Australia in late June; near the equator, the stars lose night potential from May to June; they ill-compete with the Sun in the northern tropics and sub-tropics from late February to mid-September, with March being unfavourable as to post-sunset due to the Milky Way's light.
Deepsky objects
The lack of DSO in this constellation is due to the location away from the place of the Milky Way. This location has no Messier objects.
NGC 1595 – Galaxy
NGC 1598 – Galaxy
PN G243-37.1 – planetary nebula
Main stars - 4
Bayer stars - 8
stars with planets - 1
stars within magnitude 3.0 - 0
Stars within 32Ly - 0
Bordering
constellations
The lack of DSO in this constellation is due to the location away from the place of the Milky Way. This location has no Messier objects.
NGC 1595 – Galaxy
NGC 1598 – Galaxy
PN G243-37.1 – planetary nebula
Main stars - 4
Bayer stars - 8
stars with planets - 1
stars within magnitude 3.0 - 0
Stars within 32Ly - 0
Bordering
constellations
- Columba
- Lepus
- Eridanus
- Horologium
- Dorado
- Pictor