While processing my image of NGC 7789 I came upon a very colourful double star. The double is located N-E of the open cluster. The stars have magnitudes of 9.7 and 10.8 with a separation of 18.2” (source: Washington Double Star Catalog). Here is a close up of the pair.

WDS ES 38 – September 14, 2007
Location: DAO, old 16” site.
Constellation: Cassiopeia
Optics: Borg 77EDII at f/4.3
Camera: Canon 20Da on Kenko SkyMemo.
Exposures: 56 light frames of 60 sec, ISO 800.
Process: Calibrated with 30 dark frames and 25 flat frames in ImagesPlus. Combined using MinMax Excluded. Colour balance in Photoshop.