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Ha plus OIII
Start from Ha
Start from OIII
and add OIII
and add Ha
In
the image above North is to the left, East to the bottom and
West upwards.
The
Cygnus Loop consists of a number of named objects;
The Eastern Veil (NGC6992 and
NGC6995), the
Western Veil
(NGC6960, Witch's Broom nebula) and
Pickering's Fleming's
Triangular Wisp (NGC6979).
The
Cygnus Loop is the remains of two consecutive supernova
explosions. The first supernova took place roughly 18 000
years ago followed by the second 13 000 years later.
Some 1470 ly away it spans almost 3 degrees of our skies and
90 ly in space.
I
find this region difficult to image due to the rich star
fields. After an RGB failure last year, I decided to make
new trail using narrow band filters. In addition I imaged a
few hours of RGB data, but in the end I decided on only
using the narrow band images. The reason being that the RGB
data was completely filled with stars, hiding the nebula
parts.
One advantage when using
a OIII filter on a DSLR (wich registers signal in all three
channels RGB) is that the OIII filter (Baader 8.5nm)
registers both in the blue and in the green part of the
spectra. Thus one gets both blue and green colour data.
Halpha then makes up the red channel. To make the colours
appear more "real" one can also add in some of the Halpha
signal into the blue and green.
I also
created a colour version
here. |
