Sh2-290 aka Abell 31 is a planetary nebula in the constellation of Cancer
From Wikipedia: Abell 31 (also known as Sh2-290 or PK 219+31.1) is an ancient planetary nebula in the constellation of Cancer. It is estimated to be about 2,000 light years away.
The central white dwarf has a spectral type of DAO. Abell 31 is mainly composed of hydrogen and oxygen gas. The blue oxygen occupies the central region and makes up the bulk of the nebula,
while the red hydrogen makes a ring at the nebula's edge. This object is very old, and consequently, it is very large and dim (specifically, it has a low surface brightness), and its gas is dispersing into the interstellar medium.
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Imaging Details:
Telescope: Planewave 12.5" CDK w Astrodon MMOAG and ST402ME autoguider
Camera: Apogee U16M (16803 chip) w 7-position filter wheel and Astrodon Gen II Filters
Mount: Paramount ME from Software Bisque
RGB:
RGB are 10/10/8 x 10 min per channel
Acquisition in TSX via CCD-Commander
Bulk of processing PixInsight and some final clean-up in Photoshop
Lucknow, Ontario, Canada
April 2026