NGC 6357 in Scorpius



Scope: Megrez II at f/3.3,  Location: Dos Picos Park, Ramona, CA   30 June 2006,   Camera: Artemis285

Exposure: 6 x 360 sec H-Alpha (1x1),  6 x 120 sec IR/UV Block Filter (1x1), 6 x 90 sec RGB Exposures (2x2). 

Processing: Images were captured  with Artemis Capture (as FITs).  Aligned/stacked in Registax 3 and saved as FITS. Luminance,  H-Alpha, IR/UV Block,  and Color channels were scaled and  color balanced in Astroart. Channels were co-registered in Astroart.   Central Gradient removal  was done in Astroart. Curves and Levels applied in Photoshop to optimize object features. Final LRGB combine was done in Photoshop using Luminance Layering (or LLRGB) - G2V calibration factors and Atmospheric Extinction factors were applied.  Selective sharpening was applied to nebula features in Photoshop with a layer mask.  SGBNR was used to smooth background noise on the final result.   Final Image size is approximately 1392x1040.

All exposures in this image were guided; North is up in this image. NGC 6357 is located in the constellation of Scorpius. This object appears mostly red because it is a Hydrogen Alpha emission nebula and its light travels through a fair amount of interstellar dust to reach Earth. The dust tends to reduce transmission of shorter blue wavelengths and less so the longer red wavelengths. The Horizontal FOV is 125'.

Image center is located approximately - Equatorial 2000: RA: 17h 25m 02.666s Dec: -3441'45.924"



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