I'm trying to shoot a nice "neutral oxygen" images of M27 and M57 but I constantly have some clouds just waiting for me to put the scope out...
At the moment I just have this:
[O III] and [O I]; TSAPO65; 3 minute exposures. 15 frames for [O III], 8 for [O I]:
*
[O III]
*
[O I]
[O I] 30 x 5 sec, C11 at f/6.3, bin2; no dark/flat:
http://www.rkastrofoto.appspot.com/s...012/o1-sct.jpg
It needs longer exposures, but it does look
like in the book. The [O I] at 630 nm is a "neutral oxygen" emission line, different from the commonly used [O III]. Usually it can be found glowing further away from the ionizing star/white dwarf, but in some planetary nebulae higher density condensations present in the nebula can glow in [O I] (like M27). The emission line isn't strong, similar to [S II] in intensity.
To shoot the [O I] I used a
EO bandpass filter and Baader filter for the [O III].
