Horologium, "The Pendulum Clock", is one of those obscure
constellations of the southern hemisphere invented by Nicolas Louis de
Lacaille in the mid-eighteenth century.
Like the majority of Lacaille's constellations, Horologium
is a curious asterism, and has very little to offer. There are no binaries of
any interest here, and no deep sky objects. One Mira-type variable (R
Hor) is a rather interesting star.
Its Bayer stars are few and rather faint,
ranging from 3.9 to 5.4.
R Horologium is a Mira-type variable with a very wide range.
Indeed, this star has one of the largest ranges known: from a fairly
bright 4.7 to an extremely faint 14.3 visual magnitude. The period is
407.6 days. In the year 2000 the maximum should be achieved near the end
The star is two degrees NE of iota Horologii.