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Re: (IAAC) Markarian 205 - 8inch F/10



At 09:42 AM 6/11/98 -0400, you wrote:
>
>Welcome back, Nick!
>
>You are right - the views of many objects are worsened by narrowband
filters. I 
>guess I was proposing that the reason for those worsened views was generally 
>just reduced light transmission overall - rather than any reduced contrast of 
>the object/feature relative to background. But I wonder if there may be areas 
>of some of these nebulae (Cat's Eye in particular) which do in fact emit their 
>light mainly at wavelengths outside the Hbeta and OIII regions?
It is possibly significant that both the Catseye and Eskimo nebulae are both
quite highly coloured so they must be emitting at other wavelenghts apart
from any continuum reflection. 
>One thing for certain, there are lots of "emission" nebulae whose light is 
>actually more than half reflected (continuum) starlight: using even a wideband 
>filter on these can make them disappear entirely (or make many of their 
>features - the primarily reflected ones - disappear from the object).
>
>As a matter of fact, one of my favorite observing projects is trying to 
>distinguish and map out the complex, intermingled dust- and gas-heavy 
>components of brighter nebulae, using nothing but "UHC blinking".
I also find it  a very interesting exercise when I try it.
Nick
Nick Martin, Bonnyton house, By Ayr, Ayrshire KA6 7EW ,Scotland, UK.
 Longitude 55 24'56" Latitude 4 26' 00".
"Thou star of evening's purple dome
 That lead'st the nightingale abroad,
 And guid'st the pilgrim to his home." 
   To the Evening Star by T.Campbell

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