M8 The Lagoon Nebula (NGC 6523)
Click the above image for a wider view
Very pleased with the sharp detail in this image. One of my better
ones so far. If you look closely you will see that the stars are a little bit out of
shape due to tracking errors, but overall it's not too bad. Quite a pleasing result.
The above image was acquired via 69 minutes (23x3Mins) of data from the
Canon 350D (unmodified at ISO800). The telescope I used was the Orion 80ED
refractor piggybacked on an autoguided LXD-75 SN-8. The night was cold (around -1C)
which helped to keep the noise in the camera down.
About the Lagoon Nebula
Messier object number 8, known as the Lagoon Nebula (NGC 6523) is a
diffuse emission nebula that has spawned the new bright stars of NGC 6530 (the bright
cluster of about 2 dozen stars just a bit right of centre). The dark blotches
(Bok globules) are dense interstellar dust and gas centred around one or more stars which
are about to be born. The blue-green tones in the nebula's core are caused by a
strong glow from Oxygen III, Sulphur and Hydrogen Beta emissions. The red colored
parts are where the glow of Hydrogen alpha (H alpha) is detected as being strongest.
The unmodified Canon 350D camera is most sensitive to blue-green light
such as is emitted by O-III and H-beta molecules. It is less sensitive to the red
light of H-alpha emission.
A modified Canon 350D (i.e. one which has had its infra-red filter
removed) is three times as sensitive to H alpha emission, and it would yield a much redder
image. Often more than half of the light emitted by a nebula like M8 is H alpha
(red) emission, especially in the outer regions, so a modified 350D will collect more
light, albeit toward the red end of the spectrum. In many pictures of nebula that
you'll see on other websites the pictures are taken with red-sensitive cameras, and the
blue-green light is all but swamped by red.
I like this image because in theory it would be similar to what your eye
would see if you were located in space close enough, and your eye was sensitive enough, to
get a view like this. The 350D camera (like all ordinary "family"
cameras) has been built by the manufacturer to respond to the colors of the spectrum in a
similar fashion to how our eyes respond.
At low light levels our eyes are almost blind to the deep red light of H
For other M8 images click the links below:
Lagoon Nebula 23x3 mins ISO1600 guided 18Aug06
Lagoon Nebula 23x3 mins ISO1600 guided 18Aug06 WIDE
Lagoon Nebula 23x3 mins ISO1600 SN-8 autoguided 18Aug086 CLOSEUP
M8 Lagoon Nebula (23x3 mins ISO800 guided LXD-75 - Orion ED80 19Sep06)
Trifid Nebula (M20) in widefield (2 degrees - Orion 80ED) (Guided 7 x 4mins ISO
ultra (100 mins of data over 3 nights - 3 sets of data combined - Orion 80ED Winter 2006)
Early Attempt (Guided 7x4mins ISO800 Orion 80ED 24Jun06)
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