Horologium is another constellation in the bleak regions of the southern hemisphere, generally between Achernar (in Eridanus) and Canopus (Carina). More specifically, Horologium is just west of Caelum, and east of Eridanus, and an acquaintance with either of these constellations would be beneficial to the study of Horologium. The intriguing R Horologii, a very long-period Mira variable, is the most interesting object in the constellation.
Alpha Horologii is a yellow giant, far to the north of the rest of the constellation. The star is in the same FOV as alpha Caeli, or due east of theta Eridani about two binocular fields.
Iota Horologii isn't particularly interesting in itself, a 5.4 mag yellow star 56 light years away. But it's a convenient star to find the interesting R Horologii, a Mira-type variable with very wide range. Iota is about seventeen degrees southwest of alpha, or about two and a half binocular fields. The other stars here are also 5th-mag.
R Horologii, two degrees northeast of iota, usually has a mag of only 14 or so, far too dim for most binoculars. However every 407 days it glows with a 4.7 or thereabouts magnitude. In 2000 the maximum should occur around the end of September.
