The Double Cluster is the name for two open clusters – NGC 869 and NGC 884 – located close together in Perseus constellation. Also known as h Persei and χ Persei, the clusters both lie at an approximate distance of 7,600 light years from Earth and are about 12.8 million years old. With an apparent magnitude of 3.7/3.8, the Double Cluster is visible even without binoculars in good conditions, but best observed with binoculars or small telescopes. Each cluster contains more than 300 blue-white supergiants and their hottest stars on the main sequence belong to the spectral class B0. Both clusters contain a significant number of bright, young O and B-type stars.
NGC 884 and NGC 869
Telescope: 16″ f3.75 Dream Scope
Camera: FLI ML16803
Mount: ASA DDM85
Exposure: 2.5 hours (12x300s L + 3x6x300s RGB)
Date: October 2019
Location: Southern Alps, France