With a radius of 5 light years, Cassiopeia A is a supernova remnant (SNR) in the constellation Cassiopeia and the brightest extrasolar radio source in the sky at frequencies above 1 GHz.
The SNR is located around 11,000 light years from here and was produced by a star that exploded around 300 years ago.
Imaged in LRGB Ha and OIII at Dark Sky New Mexico OTA Planewave CDK 24.
Image Processing: Mark Hanson and Mike Selby