NGC 2360 is an open cluster visible with binoculars in the constellation of Canis Major. It was the first deep sky discovery made by Caroline Herschel - the younger sister of William Herschel - on February 26, 1783. She described it as "a beautiful cluster of pretty compressed stars near 1/2 degree in diameter." It's also known as Caroline's Cluster, Caldwell 58 and Melotte 64.
William included the cluster in his 1786 catalogue of 1000 clusters, crediting his sister as the discoverer. At magnitude +7.2, NGC 2360 is not visible to the naked eye but it's an easy binocular object and a fine sight through small telescopes. The cluster is positioned 8 degrees east-northeast of the brightest star in the night sky Sirius (α CMa - mag. -1.47) and lies 3.5 degrees directly east of gamma CMa (γ CMa - mag. +4.1). At the western edge of NGC 2360 is an unrelated star, HD 56405 (mag. +5.5).
NGC 2360 appears as a smudge of light through 7x50 or 10x50 binoculars with the brightest components just about resolvable. A small 80mm (3.1-inch) scope reveals tens of stars packed in a rich round grouping that spans about 14 arc minutes in diameter. This is one cluster that handles high magnifications well, so don't be afraid to push the power up as the seeing conditions allow. Medium sized 150mm (6-inch) or 200mm (8-inch) scopes reveals at least 45 stars with many of the stars being of the same colour and roughly the same brightness. They trace nice arcs and winding paths throughout the cluster. Although not as bright as the nearby Messier open clusters (M41, M46, M47 and M93), NGC 2360 is a fine cluster for all telescope sizes.
NGC 2360 is 3,700 light-years distant and is estimated to be 2.2 billion years old. It's best seen during months of November, December, January and February.
C58 Data Table
|Object Type||Open Cluster|
|RA (J2000)||07h 17m 43s|
|DEC (J2000)||-15h 38m 29s|
|Apparent Size (arc mins)||14 x 14|
|Age (years)||2.2 Billion|
|Number of Stars||>50|
|Other Name||Melotte 64|