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Old 30-12-2010, 10:52 AM
jamespierce (James)
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Join Date: Jul 2009
Location: Australia
Posts: 321
A UHC filter shouldn't be of assistance with the nebulosity surrounding the Pleiades. It is a reflection nebula and has the same basic colour as the stars themselves. It has no emission component because the stars in the cluster don't put out enough high-energy U.V light to ionise Hydrogen (You need O3 to O9 stars to do that sort of thing). A UHC filter blocks starlight and in doing so blocks reflection nebulosity. Go without filter !

I've observed M45 a couple of times looking specifically at the nebulosity, I can see it clearly both with and without the filter, both time's I've thought it was a little more obvious with the filter - perhaps it's just a placebo of a slightly darky image overall ? I will look again with more care tonight !


You mention the cluster next to M35 -- I think this is a typo as it is NGC 2158. A distant (but quite large) open cluster that is somewhat reddened compared to M35. Believed to be a G.C up until about the 1970s when someone did a C-M diagram that showed it's decidedly "open" character.

Yup, typo (fixed) - it's beautiful though isn't it - it almost does look like a G.C.


M46 and its embedded planetary (NGC 2438) are excellent. The planetary would be an excellent target by itself.

Yup, with a bit of magnification and the OIII the cluster fades and the planetary really pops out. Very easy to find planetary for anyone wanting to find their first too.
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