SH2-188: an interesting planetary nebula in Cassiopea The image is of Sharpless 2-188 (Sh2-188), which is a peculiar planetary nebula located in Cassiopeia.
The gas expanding from the nebula is colliding with gas in the interstellar medium. The nebula is nearly circular and its South-East part (lower left) is much brighter respect the rest of the nebula because the central star is moving rapidly in that direction. Thanks to the very long exposure through a narrow band Ha filter, faint structure of gas can also be seen in the opposite direction. North is up.
The small galaxy not far from the South West part of the nebula is the PGC137850

Author: M.Angelini

Ha: 48x30' -> 1440 mins
Dall-Kirkham Astrograph 12.5" F/7.8
ATIK 11000
Gemini Mofod equatorial fork mount - Gemini Pulsar 2