While waiting for M82 to rise high enough to start my M82 imaging each night at the observatory, I thought about which object to rip in the meanwhile. So I picked a “bright” but very challenging planetary neb, specifically Abell 12 (PK198-6.1), which is 13th magnitude nestled against (30 arcseconds away!) bright 4th magnitude multiple star 16Mu Orionis (spectral class A4) just northeast of Betelgeuse (see attached chart). Visually, this is a real challenge separating the 37arcsec diameter nebula from the glare of Mu Orionis but an OIII filter sometimes does the trick as it worked miracles in Margie Wright’s 16-inch Dob this Fall. I am not aware of any such aids in separating the nebula photographically. There are not that many imaging entries on this object on the internet; a few of the best links are attached below. I would love to see Adam Block rip this with the new Mt. Lemmon 24-inch RC! My image is LRGB (all 1X1 data) consisting of only about 2 hours of total exposure (only 40 minutes of luminance) over two nights with the RC pre-M82 effort. Notice the many stars in my close-up image within the planetary nebula including the central star at magn. 19.1! Fortunately, the diffraction spike did not totally cover up the nebula! I cannot change the position of that spike; it is inherent in the design of my RC scope. If you look closely, you can see some of the red nebula on the other side of the spike! Also, notice the very faint anonymous galaxy on the opposite (east) side of the star from the planetary. Abell 12 appears red and mottled with blue patches. That was fun. Next, need to tackle M82 processing.
http://www.caelumobservatory.com/gallery/abell12.shtml — Adam Block’s Abell12
http://www.skyhound.com/sh/archive/jan/PNG_198.6-06.3.html – Abell12
http://www.astronomy-mall.com/Adventures.In.Deep.Space/abellcat.htm – Abell Planetary Neb Catalog