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two faint nebula
extremely difficult due to bright glare and reflections inside
the optical system, and the huge number of geosynchronous satellites
that run through this part of the sky. The small image here will
enlarge to my original LRGB frame to show what I had to deal
with in processing. The result of this effort is the larger image
above, with most of the flares removed.
IC423 is the
lower teardrop shaped nebula. The blue reflection nebulosity
is mixed with the ultra dim core region colored with browns and
reds from obscuring dust. Around the periphery of the core you
can see a greenish tint from the mix of inner yellow and outer
blues. IC423 is known also as LBN913, and is roughly 6 arcminutes
in length.
Above is a strangely
uniform blue patch of reflection nebulosity known as IC424. Covering
2.8 arcminutes of sky, it's serrated edges hint at invisible
dust carving into its outline. Two 12th magnitude stars illuminate
this nebula.
There is part
of a larger emission nebulosity in the lower left corner, this
part of Orion is filled with a luminous glow from red hydrogen.
Processing:
Yes - and what
an adventure this image was for sure. The techniques used for
recovering this potentially disastrous image were performed in
Photoshop CS2. First, satellite trails were removed by zooming
in to view sub pixel resolution and piece by piece the trails
were cloned out with adjacent blank sky as to not add any extra
stars. The blue "rays" were harder. Since Mintaka is
an O9 star, nearly all the rays were in the blue channel, and
nearly none in the red. This good fortune made it a straightforward
task to replace the sky in the selected regions with the red
frames sky background, using a standard layer mask to apply this
new background to only where the ray appeared. To remove the
large number of blue rays that were over the nebulas themselves
was the toughest part. The color of the rays was very close,
but not exactly the same as the blue nebulosity, and the rays
were very carefully selected with the color range command to
exclude the nebula. Then they were darkened by pulling the mid
tones down on the rays with curves so that it exactly matched
the brightness of the nebula.
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