Abell 81 is interesting because of an obscure halo best seen in Jerry Macon's version.   I shot this before with my CCD and never saw the halo but thought I saw something in my CMOS.  So I decided I would throw GHS at this and by heavily stretching the image the halo came out in spades.  However, the bright core of the PN was over saturated.  Therefore, in Photoshop, I used the heavily stretched halo version as a "Hide All" Layer Mask over the normally stretched version only allowing the halo to appear where I paint the mask with white.

I put the Layer and Original in as variations B-C.

GHS Forum Discussion

Previous version same scope but CCD camera and no unusual processing


Abell 81

For the Germans in the audience, I have a German page on the Abells and they say regarding a 27" scope view... the German page is linked below:

der PN fällt sofort und direkt im Übersichtsokular und ohne Filter als auffällige, runde Aufhellung auf; der [OIII] Filter und 293x zeigt den PN als 5:4 Ost-West elongierten Ring; bei höheren Vergrößerungen schälen sich einzelne Knoten innerhalb des unruhig wirkenden Rings heraus; das Halo ist bestenfalls bei 172x und [OIII] zu erahnen, jedoch nicht sicher zu halten

Which Google translates as:

the PN stands out immediately and directly in the overview eyepiece and without a filter as a conspicuous, round brightening; the [OIII] filter and 293x shows the PN as a 5:4 east-west elongated ring; higher magnifications, individual nodules emerge within the restless-looking ring; the halo can at best be guessed at 172x and [OIII], but cannot be held with certainty

GENERAL NOTE ON ABELL (and other) PLANETARY NEBULA>>>>>>>>>>>>>

From Wikipedia:

The Abell Catalog of Planetary Nebulae was created in 1966 by George O. Abell and was composed of 86 entries thought to be planetary nebulae that were collected from discoveries, about half by Albert George Wilson and the rest by Abell, Robert George Harrington, and Rudolph Minkowski. All were discovered before August 1955 as part of the National Geographic Society – Palomar Observatory Sky Survey on photographic plates created with the 48-inch (1.2 m) Samuel Oschin telescope at Mount Palomar. Four were later rejected as not being planetaries: Abell 11 (reflection nebula), Abell 32 (red plate flaw), Abell 76 (ring galaxy PGC 85185), and Abell 85 (supernova remnant CTB 1 and noted as possibly such in Abell's 1966 paper). Another three were also not included in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (SEC): Abell 9, Abell 17 (red plate flaw), and Abell 64. Planetaries on the list are best viewed with a large aperture telescope (e.g. 18-inch (0.46 m)) and an OIII filter.

There is an Abell Group on Astrobin. 

This is my personal collection:

Planetary Nebula (Abell)

These are sorted by number and behind the Abell's are other miscellaneous PNs that I have imaged... I have a list of the 100 brightest.

This is Gary Imm great poster on the Abell's:

Gary's Poster

This is Jerry Macon's outstanding Abell Collection:

Jerry Macon's Abell Collection

These are some useful Abell relevant sites:

Color and IMHO Best Filter Information

Images by Season and More Filter information in German