NGC 559 is a magnitude +9.5 open cluster in Cassiopeia that's faintly visible with binoculars, but better seen with telescopes. The surrounding area of sky is full of bright clusters including NGC 457, M 52, M 103, NGC 129, NGC 7789, NGC 654, NGC 663 and IC 1848. As a result, tenth magnitude NGC 559 is not a standout object. However, it's easy to find and a nice target for small and medium size scopes.
William Herschel discovered NGC 559 on November 9, 1787. The cluster is positioned towards the eastern edge of the "W" of Cassiopeia and 3 degrees north of Ruchbah (δ Cas - mag. +2.7). To the southeast of NGC 559 are open clusters NGC 654 (mag. +6.5), NGC 663 (mag. +7.1), M 103 (mag. +7.4) and NGC 659 (mag. +7.9). From most northern temperate latitudes, NGC 559 is circumpolar and therefore visible all year round. It appears highest in the sky during October, November and December.
Although visible with binoculars as a faint unresolved patch of light, NGC 559 is better seen with small and medium size scopes. A 100mm (4-inch) refractor reveals up to 15 stars superimposed on a grainy background. The brightest four stars are between 11th and 12th magnitude with another dozen between 13th and 14th magnitudes. In total, about 50 stars belong to the cluster, which spans 7 arc minutes of apparent sky. Larger apertures reveal many of the fainter stars.
NGC 559 is located 3,700 light-years distance and has a spatial diameter of 7 light-years. It's an old cluster with an estimated age of 2 billion years and is listed as number 8 in the Caldwell catalogue.
NGC 559 Data Table
|Object Type||Open Cluster|
|RA (J2000)||01h 29m 29s|
|DEC (J2000)||63h 18m 30s|
|Apparent Size (arc mins)||7 x 7|
|Age (years)||2 Billion|
|Number of Stars||50|
|Other Name||Collinder 13|