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  1. #1
    Malcolm Stewart's Avatar
    Malcolm Stewart Guest

    Default Colour visibility of M42 (Nebula in Orion)



    What aperture is necessary to clearly see (via a naked eye) the reddish
    colour in M42? Or is this dependant on local light pollution? (Pretty bad
    in Milton Keynes, and the moon was close to full.)

    I'm using a 200mm f5 Dob with a 32mm eyepiece, and earlier this morning I
    could see no suggestion of the reddish colour at all.

    This image http://www.seds.org/messier/Pics/More/m42b.jpg shows a clear
    reddish glow.

    --
    M Stewart
    Milton Keynes, UK
    http://www.megalith.freeserve.co.uk/oddimage.htm



  2. #2
    James's Avatar
    James Guest

    Default Colour visibility of M42 (Nebula in Orion)


    "Malcolm Stewart" <malcolm_stewart@megalith.freeserve.co.uk> wrote in
    message news:clk848$1j0$1@newsg1.svr.pol.co.uk...
    bad
    Not sure - certainly through my 150mm Newtonian it appears as a
    greeny-grey...



  3. #3
    andrea tasselli's Avatar
    andrea tasselli Guest

    Default Colour visibility of M42 (Nebula in Orion)

    "Malcolm Stewart" <malcolm_stewart@megalith.freeserve.co.uk> wrote in message news:<clk848$1j0$1@newsg1.svr.pol.co.uk>...

    It took me a 20" at 3000ft in a very dark location in the SW of the US
    to see a glimpse of that red colour. Green is no problem in reasonably
    darkish location with a 7".

    Best

    Andrea T.

  4. #4
    Martin Brown's Avatar
    Martin Brown Guest

    Default Colour visibility of M42 (Nebula in Orion)

    In message <ba9aa3a9.0410252217.6efcbb90@posting.google.com >, andrea
    tasselli <atasselli@hotmail.com> writes

    The strong red colour is a quirk of classical photography. The brightest
    green OIII nebula emission line is the safelight colour for panchromatic
    colour film and is not recorded. Modern CCD images give more accurate
    colour rendering they don't have the same blind spot to green OIII
    light.

    It wasn't until the early 1970's that anyone bothered to make an
    accurate colour image of M42 as it would appear to the human eye. The
    article made the front page of Scientific American as they were very
    pretty.


    I have known someone see red in an 18" scope from the UK. Most people
    myself included see it as apple green or turquoise though.

    Regards,
    --
    Martin Brown

  5. #5
    Chris.B's Avatar
    Chris.B Guest

    Default Colour visibility of M42 (Nebula in Orion)

    atasselli@hotmail.com (andrea tasselli) wrote in message news:<ba9aa3a9.0410252217.6efcbb90@posting.google. com>...

    The palest turquoise(?) coloration is always evident in my 6" f/8
    refractor under my dark skies. Red is a low sensitivity colour to the
    eye in comparison with the blue-green. But I don't think this image is
    representative of the visual view anyway.

    Judging any colour against a background fog of artificial light and
    Moonlight is not conducive to accuracy or sensitivity. I might suggest
    higher powers to help darken the background sky for increased
    contrast. You might also try one of those expensive specialised nebula
    filters to combat your own particular light pollution.

    Just in case anyone was tempted. I really wouldn't recommend British
    amateurs try to match Andrea's observing conditions. Dragging a 20" to
    the top of Snowdon just to see the red coloration in M42 is not
    sensible. Even on the train. Then you'd have to wait until the next
    day's service to get back down.
    There is not only a very poor chance of clear skies. But there are
    also a number of local towns more than willing to pollute your skies.
    Even if you do reach the summit fully instrumented.

    No doubt the Guiness Book of Records should be informed if you do
    decide to make the effort. Please god this doesn't start an extreme
    sport!Titanium/Carbon-fibre 24" sponsored Dobs with ultra-thin ceramic
    mirrors and spiked training shoes? Olympics 2008?

    So, it's still cloudy then? ;-)
    Chris.B

  6. #6
    Jim's Avatar
    Jim Guest

    Default Colour visibility of M42 (Nebula in Orion)

    In article <941cd3a9.0410260339.7878528@posting.google.com> , Chris.B wrote:

    In this month's "Extreme Astronomy":

    Pete Lawrence on 'Cliff face observing'
    Chris B on 'Cooldown Time for Mak Cas scopes on Glaciers'
    J C Andrew on "You don't need a mount in freefall"


    Um, yeah.

    Jim
    --
    Find me at http://www.ursaMinorBeta.co.uk
    "Brace yourself, this might make your eyes water."

  7. #7
    Pete Lawrence's Avatar
    Pete Lawrence Guest

    Default Colour visibility of M42 (Nebula in Orion)

    On Tue, 26 Oct 2004 12:46:20 +0100, Jim <jim@odin.magrathea.local>
    wrote:


    I can see Beachy Head from Selsey on a very, very clear day. I've got
    a photo to prove it somewhere (it's a long way away for those who
    don't know). Does this count as "Cliff face observing"?


    It wasn't last night Jim - but then of course you'd need to have your
    Moon googles on
    --
    Pete Lawrence
    http://www.digitalsky.org.uk

  8. #8
    Jim's Avatar
    Jim Guest

    Default Colour visibility of M42 (Nebula in Orion)

    In article <6ffsn0lns1saorq7akhtairk02qrqskdhs@4ax.com>, Pete Lawrence wrote:

    Not quite what I had in mind but since it's you, yeah, why not.


    It was here - nice and clear this morning though.

    Jim
    --
    Find me at http://www.ursaMinorBeta.co.uk
    "Brace yourself, this might make your eyes water."

 

 

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