The Great Nebula in Orion (M42) and NGC 1977 (Running Man
Nebula)
All Images Copyright Steve
Cannistra
Please
click
here
or on image for a higher resolution vertical view (693 x 1375).
Please
click
here
for the highest resolution vertical view (990 x 1964).
Please
click
here
for a higher resolution horizontal view (1375 x 693).
Please
click
here
for the highest resolution horizontal view (1964 x 990).
Characteristics:
Magnitude: 5.0
Size: about 1.5 degrees (for the final mosaic)
Distance: 1600 light years
RA: 5h 35m
Dec: minus 5 degrees 35' 54"
Description:
This is my latest image of the M42 complex, representing a two frame
mosaic and about 6.5 hours of exposure time. The Great Orion
Nebula is the brightest nebula visible to the naked
eye, forming the middle part of the Hunter's sword in the famous
constellation Orion.
It is a breathtaking view in even small telescopes, where
tendrils of gas can be appreciated even without the aid of special
filters. The use of a UHC filter improves contrast significantly
and reveals a
significant amount of faint nebulosity during visual observation.
The typical visual view in a telescope is pale white to faint
green, due to the human eye's poor color response to low light
(especially
in the red, which is emitted by this nebula due to excitation of
hydrogen
gas as a result of radiation from newly formed stars). In this
view,
The Great Orion Nebula (M42) is on the right, de Mairan's Nebula (M43)
is just below center, and the Running Man Nebula (NGC 1977) is on the
left, a beautiful
reflection
nebula that derives its blue color from reflected light of nearby
stars. Please be sure to check out the links under the photo for
higher resolution views.
Photographic Details:
Date: December
15 and December 17, 2004.
Scope: Takahashi
Sky 90 at f4.5 with field flattener/focal
reducer, on a Losmandy G11 mount.
Autoguider: STV
with e-finder.
Camera: SXV-H9.
Filters: Ha
(13nm bandpass), L, R, G, B type II filter set, all from Astronomik.
Exposures (all
unbinned): December 15 (the right hand side of the mosaic):
22 x 4' luminance; 20 x 30" luminance; 6 x 4' each R, G, B; 20 x 30"
each R, G, B; 6 x 5' Ha; 20 x 30" Ha. December 17 (the left
hand side of the mosaic): 20
x 4' luminance; 6 x 4' each R and G, 8 x 4' B. Total exposure
time about 6.5 hours.
Conditions: In a
word- glorious (except for the temperature,
which was 18-20 degrees F on both nights). I've never had
transparency and seeing conditions like this. No clouds. No
wind. After the moon set,
the sky was inky black,
and the stars hardly twinkled....
Post-processing:
LHa:(LHa:R:G:B)- please see below for details. No darks, flats,
or bias
frames required. Alignment,
combining (min/max excluded averaging), and DDP done
in ImagesPlus. Levels,
curves,
and
layer mask adjustments in Photoshop. Processing this image
required several techniques, which were straightforward but time
consuming. These included: 1) Making layer masks using the
shorter 20 x
30" luminance, RGB, and Ha exposures for the Trapezium region.
The 30" Ha exposures were needed to provide good definition of the
Trapezium itself; 2) Sharpening using a combination of high pass
filtering
(radius of only 2 pixels, using Overlay mode in PS) and unsharp masking
(amount 80% and radius
1.5) applied selectively to certain regions. The image was quite
smooth and permitted sharpening without introducing too much
noise; 3) The luminance channel was comprised of L plus Ha,
restricting the Ha contribution to about 50% opacity. This LHa
luminance component was combined with the RGB in Photoshop as a
standard luminosity layer (i.e., I did not use the technique of Luminance
Correction for this image, since there was reasonably good
matching between luminance signal and color). After boosting the
color saturation of the RGB component, a mild guassian blur was applied to the color layer, the image was flattened (now representing an
LHa:R:G:B layer), and it was then used as color for another LHa
luminance channel (this is a modification of a
technique
developed by Rob Gendler). Thus, the final image is LHa:(LHa:R:G:B), which resulted in good
preservation of detail and color; 4) Registration of the two frames was done in Registar,
prior to
mosaic construction.
Please
note: Graphics on this website may not be reproduced without
author permission.
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