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For the giant sundial built by Augustus, see Solarium Augusti.
Abbreviation Hor
Genitive Horologii
Pronunciation /ˌhɒrɵˈlɒiəm/,
genitive /ˌhɒrɵˈlɒi/
Symbolism the Pendulum Clock
Right ascension 3
Declination −60
Family La Caille
Quadrant SQ1
Area 249 sq. deg. (58th)
Main stars 6
Stars with planets 2
Stars brighter than 3.00m 0
Stars within 10.00 pc (32.62 ly) 1
Brightest star α Hor (3.85m)
Nearest star GJ 1061
(11.99 ly, 3.66 pc)
Messier objects none
Meteor showers ?????
Visible at latitudes between +30° and −90°.
Best visible at 21:00 (9 p.m.) during the month of December.

Horologium is a small and faint constellation in the southern sky (declination around −60 degrees). Its name is a Latin transliteration of the Greek [1] word for clock (Horo [ὥρο]- meaning hour and logium [λέγειν] meaning teller [horologium= the hour-teller]).


Horologium was plotted in the 18th century by Abbé Nicolas Louis de Lacaille.[2] He originally labeled it Horologium Oscillitorium, the Latin name for a pendulum clock, to honour its inventor Christiaan Huygens and his book Horologium Oscillatorium.

Notable features[edit]

The constellation Horologium as it can be seen by the naked eye


Horologium does not have any bright stars. Alpha Horologii, the brightest, is an orange giant of magnitude 3.9, 117 light-years from Earth. Beta Horologii is a white giant of magnitude 5.0, 314 light-years from Earth. However, Horologium does have several variable stars. R Horologii is a red giant Mira variable with a very wide range, 1000 light-years from Earth. It has a minimum magnitude of 14.3 and a maximum magnitude of 4.7; its period is approximately 13 months.[2]

Deep-sky objects[edit]

Horologium is also home to many deep-sky objects; there are several globular clusters in the constellation. NGC 1261 is a globular cluster of magnitude 8, 44,000 light-years from Earth.[2] The globular cluster Arp-Madore 1 is found in the constellation, the most remotely known globular cluster in the Milky Way at a distance of 398,000 light years.

See also[edit]


  1. ^ Smith, William (1875). A Dictionary of Greek and Roman Antiquities. London: John Murray. pp. 615‑617. 
  2. ^ a b c Ridpath & Tirion 2001, pp. 156-157.

External links[edit]

Coordinates: Sky map 03h 00m 00s, −60° 00′ 00″