I copy my observing notes from my still in progress revision of my old (and faulty) Abell PN Project.
PN: Abell 31 (PNG 219.1+31.2, PK 219+31.1, Sh 2-290)
4" Binocular Telescope, 23x, [OIII], NELM 6m5+ with [OIII] filter easy visible as a round and diffuse glow around the 10mag bright GSC 8112166; the 10' large glow seems to be a little bit brighter towards the SW edge but is to small for the given aperture to resolve more structure; the whole glow is steadily visible with averted vision
8", 31x, [OIII], NELM 6m5+ large and easy visible glow with direct vision and [OIII] filter; positioned along an parallelogram of 10mag stars; brightest part seems to be east of the SE star of the parallelogram and is elongated 1:2 north-south; west following another fainter part is visible; the western part runs out very diffuse; all in all the whole nebula is around 14' large
16", 51x, [OIII], NELM 6m5 bright glow with maximum EP and [OIII] filter; positioned around a 10mag star; nebula shows some structures - brightest part to the west to SW of the mentioned star; very diffuse edges; at the NE a second smaller part is visible
27", 113x, [OIII], NELM 6m5+ visible even without filter as a faint glow around a 10mag star; positive and good response to [OIII] filter, only moderate response to UHC filter and no response to Hß filter; with maximum EP (and field) plus [OIII] filter the whole glow shows a mottled structure, broken with some difficult to locate dark lanes; brightest part is positioned directly SW of the star; another part is positioned NE and moves along the star; a third part is positioned at the SE end of the PN; the photographic striking H? shell at the SE side is not visible with all filter combination
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