The Lagoon Nebula
The Lagoon Nebula


Explore Scientific 127mm at f/7.5


Losmandy G11


Starlight Xpress SXVR-H18


Baader Ha, 7nm


July 2011


Beckwith, Ontario


L.M. 5.6



The Lagoon Nebula is a giant interstellar cloud in the constellation of Sagittarius. It is characterized as an emission and HII region and contains young star clusters. It lies 5200 light years away and spans roughly 110 by 50 light years. This means that it's apparent diameter is more than three full moons. At visual magnitude 6 it is visible to the naked eye under sufficiently dark skies. The nebula's distinctive Bok globules are evidence of collapsing dust and gas where new stars may be forming. These globules appear as silhouettes in front of the emission nebula. A violent storm rages as radiation from new stars ionizes surrounding gas, heating it and thrusting it outwards to colder gas and dust. This results in twisted cloud formation that remarkably looks like a tornado here on Earth. This is especially evident in the south eastern areas of the nebula (lower left in image).

This image is the beginning of a project to image the Lagoon nebula. The plan is to capture the object in true color and enhance the nebulosity using data acquired through a hydrogen alpha filter. Since conditions were not favorable, I started capturing the hydrogen alpha data first during July 2012. I didn't get another chance to make it out to my usual dark sky site until a month later and by this time the Lagoon nebula was far too close to the horizon to bother capturing any RGB color data. It will have to be captured later when the Lagoon nebula is once again higher in the sky.

In the meantime I have worked on the hydrogen alpha data captured with my 5 inch apochromatic refractor and a Baader 7nm hydrogen alpha filter. With careful processing I managed to create a color image out of just the one color channel. This image was captured with little time to spare and with less than ideal seeing conditions. Accordingly I captured it with the pixels binned 2x2 in order to decrease the imaging time and reduce the star bloat that poor seeing causes. Next summer I will try again with the camera set to full resolution and capture even more detail than is seen here. Upon careful examination the stars are a bit too pink for my liking, but I am happy with the noise in the image. This is my first attempt at capturing an image in the hydrogen alpha spectrum and processing it to appear in color while the stars remain white. While the nebula really "pops" and is quite close to its actual color, there is no color variation in any of the stars which is typical of an image only acquired in one color channel.

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