M17 - Omega Nebula

M17 - Omega Nebula: The Omega (or Swan) nebula in the constellation Sagittarius is one of several bright emission nebulae in the direction towards the Milky Way's center. As the gas cloud collapses, the first stars to form are the very luminous, but short-lived, blue stars that light up the remaining gas with intense ultraviolet light, causing the gas to re-radiate at longer wavelengths, mostly in the H-alpha (red) color.

Messier: 17
NGC: 6618
Right Ascension: 18h 20m
Declination: -16° 10.5'
Apparent Magnitude: 6.0

Date: April 2010
Equipment:
Telescope: Meade 16" Schmidt Cassegrain with f6.3 reducer
Camera: SBIG ST-10XE
Guiding: Meade 5" refractor/DSI Pro/PHD

Exposure: R:V:B = 12:12:10 in 2 minute subframes.
Processing Notes: The camera was at -30°C. Data acquisition with CCDSoft. Reduced and aligned in CCDStack. Subs combined in Sigma Beta. RVB combined in AstroArt at auto-white-ballance ratio, and saved as a TIFF for import into Photoshop. Adjusted curves and levels, decreasing green slightly, and increasing red slightly. gaussian blur on the dim areas and sharpening on non-star bright areas. Slight, faded, minimum filter to reduce star sizes.
Scale: ~1.0"/pixel

Links to images of this object on other sites:
http://apod.nasa.gov/apod/ap021210.html

Additional Comments: This is the beginning set of data for M17. Not much time yet, but the background was smoothed successfully. A previous image, taken in 2008, with a 10" LX200 is shown here. http://www.fortlewis.edu/observatory/image_detail.asp?ID=85 The R filter in the photometric set is significantly sensitive in IR, so many of the cooler stars show up in this image as very red stars, where they might not be seen at all with a "photographic" red filter. The other significant difference in color balance is that [OIII] is detected more in the V ("visible", or green) filter than the B, or "blue" filter.

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