NGC 520 (ARP 157) is a pair of highly disturbed colliding spiral galaxies situated around 100 million light years away in the constellation of Pisces.
The collision is estimated to have started between 300 and 400 million years ago and is in the middle of merging with the nuclei of the two galaxies still no fully merged.
There is a very prominent dust lane within the merged galaxy, and there are a number of tidal tails and star streams that are evident.
Imaged in LRGB on my Planewave CDK 1000 at Observatorio El Sauce, Chile.
Image Processing and Acquisition: Mike Selby