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Monday, June 21, 2010

M17, the "Omega nebula"

M17, imaged with the Northern Galactic members remote telescope in Australia.
The Omega Nebula, also known as the Swan Nebula or the Horseshoe Nebula, cataloged as Messier 17 and NGC 6618.  This H-II region loactes in constellation Sagittarius. Distance from Earth is between 5000-6000 light years and it spans about 15 light years in diameter. Image area is 30'x30', about half a degree.
Open cluster of 35 hot young stars lies inside of the nebula and causes ionization glow of the elements.
The image is in HST-palette from the emission of ionized elements, R=Sulfur, G=Hydrogen and B=Oxygen

Natural color composition from the emission of ionized elements, R=80%Hydrogen+20%Sulfur, G=100%Oxygen and B=85%Oxygen+15%Hydrogen to compensate otherwise missing H-beta emission.
This composition is very close to a visual spectrum.

The telescope and technical information:

16" RCOS ja Apogee U9000 camera. 
LRGB combo.
H-alpha 6x1200s, Dark and Flat calibrated.
O-III 1x1200s, Dark calibrated 
S-II 2x1200s, Dark calibrated
Raw data is shared with Petri Kehusmaa and J-P Metsavainio

Processing workflow:
Image acquisition, MaxiDL
Stacked and calibrated in CCDStack.
Deconvolution with a CCDSharp, 30 iterations
Levels, curves and color combine in PS CS3.
Seeing was not good at the time of imaging, FWHM 5"

100% crop from the image of M17

I made an experimental starless image to show the actual nebulous better.

M17 with a suppressed Stars.

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