NGC 6894 planetary nebula in Cygnus. The extended "nebulosity" is felt to represent interaction of the PN with the interstellar medium (ISM), and perhaps the stripping of the PN halo by the ISM. This type of interaction is rarely captured in amateur images.
http://mnras.oxfordjournals.org/content/289/3/665.full.pdf

The extended Ha feature to the South of NGC 6894 was discovered by the Galactic Planetary Nebula Halo Survey (GPNHS) team using this image in July 2016.



Imaging Camera: QSI640 wsg
Imaging Scope: 9.25" Celestron edge at F/10
Guide Camera: SX Lodestar x 2, PHD2
Mount:Avalon M Uno
Filters: Astrodon
Exposure: Two hours luminance and 2 hours RGB, 3 minute subs binned x 2. Four hours 5nm Ha, 1 hour subs binned X4
Processing: CCD Stack and PS CS2.
Date: 7/25 and 7/27/16
Location: My front driveway. Morristown, NJ