“The Omega Nebula, also known as the Swan Nebula, Checkmark Nebula, Lobster Nebula, and the Horseshoe Nebula (catalogued as Messier 17 or M17 or NGC 6618) is an H II region in the constellation Sagittarius. It was discovered by Philippe Loys de Chéseaux in 1745. Charles Messier catalogued it in 1764. It is by some of the richest star fields of the Milky Way, figuring in the northern two-thirds of Sagittarius.The Omega Nebula is between 5,000 and 6,000 light-years from Earth, and it spans some 15 light-years in diameter. The cloud of interstellar matter of which this nebula is a part is roughly 40 light-years in diameter and has a mass of 30,000 solar masses. The total mass of the Omega Nebula is an estimated 800 solar masses.It is one of the brightest and most massive star-forming regions of our galaxy. Its local geometry is similar to the Orion Nebula except that it is viewed edge-on rather than face-on.” – Wikipedia (abridged)
This is an LRGB image. I had a lot of imaging time on this nebula, at 26.5 hours, as it was favourably located in the early evening with a run of clear weather. This produced a very good SNR and made dealing with noise much easier in the processing. I played around with using the Ha to enhance the LRGB image, whereby the broadband red is extracted from the Ha and this is used to enhance the red channel witha Boost Factor. I tried a wide range of boost factors and was never really happy that it enhanced the image, just making it redder, but it did detract from some of the delicated blue and yellow colours. In the end I decided that the LRGB image should be left untouched, but I show the starless Ha image, Revision D, as a mouse over, which is the purest way of showing the hydrogen distribution.
My thanks to
@Rodney Watters for his review of the original version and helpful suggestions.
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