The constellation's brightest star—and the only one brighter than an apparent magnitude of 4—is Alpha Horologii (at 3.85), an aging orange giant star that has swollen to around 11 times the diameter of the Sun.

He devised fourteen new constellations in previously uncharted regions of the southern celestial hemisphere, which were not visible from Europe.

In the mid-19th century, English astronomer Francis Baily removed the designations of two—Epsilon and Theta Horologii—as he held they were too faint to warrant naming.

In 1879, American astronomer Benjamin Apthorp Gould assigned designations to what became Mu and Nu Horologii as he felt they were bright enough to warrant them.

[12] German astronomer Johann Elert Bode depicted it as the pendulum of the clock, while Lacaille made it one of the weights.

[12] At magnitude 5.0, Beta Horologii is a white giant 63 times as luminous as the Sun with an effective temperature of 8,303 K.[16] It is 312 (± 4) light-years from Earth,[20] and has been little-studied.

[17] Lambda Horologii is an ageing yellow-white giant star of spectral type F2III that spins around at 140 km/second, and is hence mildly flattened at its poles (oblate).

[12] With a magnitude of 5.24,[22] Nu Horologii is a white main sequence star of spectral type A2V located 169 (± 1) light-years from Earth[23] that is around 1.9 times as massive as the Sun.

R Horologii is a red giant Mira variable with one of the widest ranges in brightness known of stars in the night sky visible to the unaided eye.

[18] The Astronomical Society of Southern Africa reported in 2003 that observations of these two stars were needed as data on their light curves was incomplete.

[32] HD 27631 is a Sun-like star located 164 (± 0.3) light-years from Earth[33] which was found to have a planet at least 1.45 times as massive as Jupiter that takes 2,208 (± 66) days (six years) to complete an orbit.

It contains over 20 Abell galaxy clusters and covers more than 100 deg2 of the sky, centered roughly at equatorial coordinates α = 03h 19m , δ = 50° 2′.