This month we'll begin a tour of the Caldwell objects. The objects listed should be easily visible between the onset of darkness until at least 11 pm unless otherwise noted. Some objects will be low on the southern horizon.
Caldwell 41 (The Hyades Cluster) - The Hyades (in Taurus) is a large open cluster spanning over 5 degrees. It's the closest star cluster to our solar system at a distance of about 150 light years, and contains 300-400 stars (see image on right). It's bright and easy to find (look about two-thirds the way between the belt stars of Orion and The Pleiades. Binoculars will probably give the best view.
Caldwell 73 (NGC 1851) - This relatively bright (mag 7.3) globular cluster probably would have made Messier's list if not for its southern location. The cluster never gets very high in the southern sky, so it's best to look for it between 8 and 9 pm. It's in the western portion of Columbia roughly mid-way between epsilon Columbae and alpha Caeli. You'll need a dark sky to find these guide stars, but once you're in the neighborhood, the cluster is easily found.
Caldwell 31 (IC 405, The Flaming Star Nebula) - Often photographed, C31 is a region showing both emission and reflection nebulosity. It's not hard to find the region where the nebula resides. From Elnath (in Auriga) go 5 degrees SSE to 4th magnitude 15 Aurigae, then continue on the same line for one more degree to 6th magnitude HIP24575. The nebula is as long as the Moon and about a third as wide. I could see no distinguishing features through my 16" other than a faint haze surrounding several of the stars in the region.
Caldwell 49 (NGC 2237, The Rosette Nebula) - Another often imaged nebula, the Rosette (pictured to the right) is far easier to see than the Flaming Star. The nebula and star cluster (C50, NGC 2244) can be found along a line extending from Mintaka (the right-most star of Orion's Belt) through 8 Monocerotis (the nebula is about 1.5 degrees past 8 Mon. An OIII filter will bring out some features of the region; however, the light from the Ha regions is sufficiently bright to see with a modest-sized scope.
Caldwell 50 (NGC 2244) - C50 is the star cluster in the center of the Rosette Nebula. It is easy to find and distinguished by 6 bright (mag. 6 to 8) stars that seem to form the letter 'H'.
Caldwell 46 (NGC 2261, Hubble's Variable Nebula) - Draw a line from Bellatrix through Betelgeuse and continue for another 10 degrees and you'll find this small nebula. It has an angular shape (like a filled 'V'). If you scan too far east, you'll come upon the Christmas Tree Cluster. Go west about one degree from the cluster and you'll find the nebula.
Caldwell 58 (NGC 2360) - This easy-to-find (mag. 7.2) cluster is about 8 degrees from Sirius just South of a line extending from Mirzam through Sirius. The cluster is rose-like, containing 60 or so visible stars, in several arcs consisting of 3-4 stars each.
Caldwell 64 (NGC 2362, Mexican Jumping Bean Cluster) - This month's final target is a bright (mag. 4.1) open cluster in Canis Major. It's an easy find - just 2.75 degrees ENE from Wesen (the star at the base of the dog's tail). The cluster is small (only 8 arc-minutes in size) and consists of about 60 stars (I easily saw at least 20 through my 16"). There's a magnitude 4 star (Tau Canis Majoris) in the center of the cluster. If you tap your telescope while observing the cluster, the bright star will jump around, while the dimmer stars seem to remain in place (due to a phenominon known as persistance of vision. Hence the name, Mexican Jumping Bean Cluster).
