RA 01h 44 m 00 s
Dec +61º 53′ 06.1”
RA 01h 44 m 04 s
Dec +60º 40′
Alternate: Caldwell 10, The Horseshoe Cluster
RA 01h 46.3 m
Dec +61º 13′
NGC 663 is a large open cluster compared with NGC 654 and 659. NGC 654 and 659 are small and NGC 659 is significantly dimmer than the three clusters. All are visible using a 10×50 binoculars in dark skies, although NGC 659 will pop in-and-out with averted vision. Even in a 12×60 binocular, NGC 659 needs good dark skies, since it has no stars brighter than mag 10.4. NGC 654 is barely seen as non- stellar and 663 is large and fairly bright with a handful of stars resolvable. In a 15×70 binocular, NGC 659 is seen but just very faintly. NGC 654 has one bright star to the south with a faint glow to the northwest and NGC 663 has several pairs resolved with a faint glow all around them.
NGC 654 was discovered by William Herschel in 1787.It is 7,830 light-years away. It is a very young cluster, with an age between 14 to 15 million years. The cluster has approx. 80 members.
NGC 659 was discovered by Caroline Herschel in 1783.
NGC 663, also known as Caldwell 10, is a young cluster of about 400 stars. The largest cluster of CD-B-14, it spans about a quarter of a degree across the sky. Backyard astronomers with dark skies reportedly have detected NGC 663 with naked eye observing, although 10×50 or 12×60 binoculars bring out more detail. The brightest members of the cluster can be viewed with binoculars. It is located about 6,850 light-years distant with an estimated age of 20–25 million years.
Author Stephen James O’Meara, in his book The Caldwell Objects,wrote he was able to spot NGC 654 and NGC 659 with 7×35 binoculars, but with some difficulty. This author was not able to duplicate this observation primarily due the lack of a suitable pair of 7×35 binoculars. The reader is invited to attempt this challenge.
All three open clusters are members of the Perseus Arm of the Milky Way. I was never able to obtain an astrophoto of this pair could not be obtained during the preparation of my ill-fated Cosmic Duets book in Spring, 2017 due to bad weather.