Monoceros (moh-NO-ser-us) the Unicorn covers 482 sq. metres of sky lying between Orion and Canis Minor. The name Monoceros is Latin for a Greek word meaning “one horn”.
There are many open clusters in this region, I will mention a few visible with binoculars or small telescopes. There are numerous nebulae yet no globular clusters, and the few galaxies known are too faint for our amateur instruments to observe.
Alpha Monocerotis is a 3.9 magnitude orange giant. Beta Mon is a fine triple star easy to separate with a small telescope, it forms a curving arc of blue white stars of magnitude 4.6/5.0/5.4.
Epsilon Mon (also known as 8 Mon) is another triple star, easily observed as a double with small scopes, the stars are unrelated yellow, pale yellow and blue white colour. A star is 4.4mag, B star 6.7, C star 12.7.
M50 open cluster mag 6.3, approximately 50 stars, best viewed with small telescope or binoculars.
Open clusters like M50, shown above, typically contain hundreds of stars, many of which are bright, young, and blue. In fact, most of the bright blue stars in the above picture belong to M50, but most of the dimmer, red stars do not. M50 lies about 3000 light-years from Earth and is about 20 light years across. (Extract from: http://apod.nasa.gov/apod/ap970128.html)
NGC 2237 “The Rosette Nebula” is a brilliant object when seen in long exposure photographs, however not so impressive in our telescopes. An OIII filter and a 250 mm (10 inch) telescope or larger should help bring out the nebulosity. Amateur telescopes will reveal only the brightest parts of the nebulosity and each part has a NGC number, thus the Rosette includes NGC 2237/46. In the centre of the nebula is the open cluster NGC 2244 visible with the naked eye and is a good binocular object. The 6 brightest stars form a rectangle.
At the edge of a large molecular cloud in Monoceros, some 5,000 light years away, the petals of this rose are actually a stellar nursery whose lovely, symmetric shape is sculpted by the winds and radiation from its central cluster of hot young stars. The stars in the energetic cluster, cataloged as NGC 2244, are only a few million years old, while the central cavity in the Rosette Nebula is about 50 light-years in diameter. (Extract from: http://apod.nasa.gov/apod/ap080214.html)
NGC 2264 The Christmas Tree open cluster, named because of its triangular shape is visible with binoculars. On the northern end find the bright star of mag. 4.7 S Mon, it has a close companion of 7.6 mag visible with a small telescope. The Cone Nebula which surrounds the cluster is too faint to see with our amateur scopes.
Pictured as a star forming region cataloged as NGC 2264, the complex jumble of cosmic gas and dust is about 2,700 light-years distant and mixes reddish emission nebulae excited by energetic light from newborn stars with dark interstellar dust clouds. Where the otherwise obscuring dust clouds lie close to the hot, young stars they also reflect starlight, forming blue reflection nebulae. The image spans about 3/4 degree or nearly 1.5 full moons, covering 40 light-years at the distance of NGC 2264. Its cast of cosmic characters includes the Fox Fur Nebula, whose convoluted pelt lies below center, bright variable star S Mon immersed in the blue-tinted haze, and the Cone Nebula near the tree’s top. Of course, the stars of NGC 2264 are also known as the Christmas Tree star cluster. The triangular tree shape traced by the stars appears here with its apex at the Cone Nebula and its broader base centered near S Mon. (Extract from: http://apod.nasa.gov/apod/ap120410.html)
NGC 2346 is a bipolar planetary nebula, I challenge those with 150 mm or larger telescope, it will be very faint and rectangular in shape, with a bright central star.
It may look like a butterfly, but it’s bigger than our Solar System. NGC 2346 is a planetary nebula made of gas and dust that has evolved into a familiar shape. At the heart of the bipolar planetary nebula is a pair of close stars orbiting each other once every sixteen days. The tale of how the butterfly blossomed probably began millions of years ago, when the stars were farther apart. The more massive star expanded to encompass its binary companion, causing the two to spiral closer and expel rings of gas. Later, bubbles of hot gas emerged as the core of the massive red giant star became uncovered. In billions of years, our Sun will become a red giant and emit a planetary nebula – but probably not in the shape of a butterfly, because the Sun has no binary star companion. (Extract from: http://apod.nasa.gov/apod/ap991012.html)
Collins Stars & Planets, Ridpath & Tirion 2000; Hartung’s Astronomical Objects for Southern Telescopes, Malin & Frew 1995; The Messier Objects; Stephen James O’Meara, Cambridge University Press 1998, Skywatching, David H Levy, US Weldon Owen, 1995.