Round and rich
This weekò??s small-telescope target is globular cluster NGC 2808 in the southern constellation Carina the Keel. It shines at magnitude 6.2 and has a diameter of 13.8'. That means it covers 20 percent as much of the sky as the Full Moon.
This magnificent object ò?? the skyò??s 10th-brightest globular cluster ò?? is visible to sharp-eyed observers under a dark sky without optical aid. It lies in an incredible star field 3.7ÒÀ west of magnitude 3.1 Upsilon (ß?) Carinae.
Although the cluster is bright, youò??ll have difficulty resolving NGC 2808ò??s stars through any telescope smaller than a 14-inch.
But you donò??t need to resolve the stars for this to be a beautiful small-telescope sight. A 4-inch scope ò?? crank the magnification past 150x ò?? shows a blazing core surrounded by an unevenly illuminated halo.
Round-ish with a bonus
This weekò??s first large-scope object is elliptical galaxy NGC 2986, which lies in the skyò??s largest constellation, Hydra the Water Snake. It shines at magnitude 10.8 and is slightly out-of-round, measuring 3.2' by 2.6'.
To view this target, point your telescope 6.7ÒÀ south-southwest of magnitude 4.1 Upsilon1 Hydrae. No amateur instrument will reveal a lot of detail in this object, but what you will see is an evenly illuminated central region that spans more than three-quarters of the galaxyò??s total diameter. The thin outer halo is visible at magnifications above 150x through 10-inch and larger scopes.
When youò??re through with NGC 2986, bump up the power a bit and observe the magnitude 14.4 spiral PGC 27873, which lies 2' west-southwest of the brighter elliptical galaxy.
I assure you, it is visible
This weekò??s second large-telescope target is the Sextans Dwarf, a dwarf spheroidal galaxy in the constellation Sextans the Sextant. And itò??s a tough catch.
Youò??ll find this faint target 1.8ÒÀ southeast of magnitude 4.5 Alpha (ÞÁ) Sextantis. Astronomers discovered it in 1990 during a photographic survey. It lies only 320,000 light-years away (close for a galaxy), and it ò?? dare I say ò?? ò??shinesò?? at magnitude 10.4, but itò??s so large that it has a surface brightness barely above that of the night sky.
How large? This object measures a whopping 26.9' by 5.9', meaning it covers two-thirds the area of the Full Moon. To see it, youò??ll need at least a 16-inch telescope. Insert your lowest-power eyepiece and slowly scan the area, looking for a tiny increase in the background glow.