Combination of 20, 3 minute exposures.
SBIG STL-1001E CCD. 20" f/6.8 Dall-Kirkham cassegrain telescope at prime focus.
Abell 39 is a large planetary nebula in Ophiuchius. Like all Abell planetaries, it has a very low surface brightness, although not as bad as many. The published magnitude is 16.5, but it is a relatively small 1.0 arc minutes in diameter, making the nebula slightly brighter than most Abell planetaries. Even so, it is only faintly recorded in the image above.