Site hosted by Angelfire.com: Build your free website today!

 

 

 

 

 

 

 

 

Lying just 1.5 degrees east of the better known Lagoon Nebula in Sagittarius is this beautiful complex of nebulosity comprised of IC4684, IC1274, IC1275, IC4685, b303, NGC6559 and PK6-2.1.  This rich region of the sky combines red emission nebulae with regions of blue reflection nebulosity.  At the heart of IC4685, the dark nebula B303 meanders past a magnitude 7.3 star; one of several in NGC6559's open cluster whose visible and ultraviolet radiation powers this glowing complex.  At the left of this image, a tiny magnitude 16.0 planetary nebula marks the location of a red giant star that explosively cast off its outer layers.

 

Image info

Telescope:  Orion 80ED apochromatic refractor at f/7.5

Focus:  Prime focus

Filter:  Astronomik Hydrogen Alpha 13nm FWHM, Astronomik RGB.

Mount:  Vixen GPD with Skysensor2000

Camera:  Artemis 285 CCD camera

Guiding:  700mm refractor guidescope, SAC7 camera, autoguided with Guidedog software

Exposure:  Total 150 mins (30 x 300s) H-alpha, 33, 39, 93 mins R,G,B.

Date:  6th & 7th July 2006

Processing:  For all frames, offset and flat fielding, registering and stacking done in IRIS.  No dark frames.  RGB combination is first done in IRIS, and star colours are calibrated with a G2V star.  LRGB compositing, curve stretching,  Levels, Smart Sharpen in Photoshop CS2. 

LRGB compositing is through the process of "Luminance Corrected LRGB" as described by Steve Cannistra.  The R component of the RGB is first mixed with H-alpha in Photoshop and then recombined into a new RGB.  The Luminance layer was H-alpha mixed with desaturated RGB and with a correction layer whose opacity is reduced in subsequent iterations.  Pls see the link above for details.

 

Comments

 

 

 
Copyright 2003 to 2012, by TG Tan.  All rights reserved.  Copyright exists in all original material available on this website.  This material is for your personal individual, nonprofit use only.  Redistribution and/or public reproduction of this material is strictly prohibited without prior express written permission from the author.