I was amazed by how much information is known about this low surface brightness planetary nebula that essentially looks like a soap bubble.  Located in the constellation of Hercules, it is the 39th entry in George Abell's 1966 Abell Catalog of Planetary nebulae, thus its name, Abell 39.  It is estimated to be about 3,300 light-years from earth.  It is almost perfectly spherical and is also one of the largest known spheres with a radius of about 1.3 light-years. However, the eastern limb of the nebula is 50% more luminous than the western limb. Additionally, irregularities in the surface brightness are seen across the face of the shell. The source of the east–west asymmetry is not known but it could be related to the offset of the central star

Its central star (clearly seen in the image) is slightly west of center by about 2″ or 0.1 light-years.  This offset does not appear to be due to interaction with the interstellar medium, but instead, it is hypothesized that a small asymmetric mass ejection has accelerated the central star.  The bright rim of the planetary nebula has an average thickness of about 10″.1 or about 0.34 light-years. There is a faint halo that extends about 18″ beyond the bright rim giving a complete diameter of around 190″ under the assumption that this emission is uniform around the planetary nebula. This planetary nebula has been expanding for an estimated 22,100=10.5px years.  Background galaxies are visible near the nebula (I can barely see a couple), and some can be seen through the translucent nebula (not in my image). 

This is the first time I performed 600s guided subs for the OIII data and it worked out great.  However, I was only able to integrate a small total amount of data due to the weather in Florida this time of year.   Despite that, I was really happy with the result as many of the features know about this seemingly simple circle of an object can be observed in this image, especially if you zoom in.