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NGC6992/5 the Eastern Veil Nebula, in hydrogen alpha light.

These glowing filaments of interstellar shocked gas are part of a larger spherical supernova remnant known as the Cygnus Loop or the Veil Nebula -- expanding debris from a star which exploded over 5,000 years ago.  The Veil Nebula is some 1,400 light-years away toward the constellation Cygnus.  At that distance, witnesses to the original stellar explosion would have seen a star in the heavens increase in brightness to about -8 magnitude, roughly corresponding to the brightness of the crescent Moon.

 

Image info

Telescope:  Orion 80ED apochromatic refractor at f/7.5

Focus:  Prime focus

Filter:  Astronomik Hydrogen Alpha 13nm FWHM

Mount:  Vixen GPD with Skysensor2000

Camera:  Modified Canon EOS 300D, at ISO800

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

Exposure:  Total 86 mins (43 x 120s)

Date:  30th July 2005

Processing:  RAW file conversion, Offset and Dark subtraction, flat fielding, registering and stacking done in IRIS.  Only the Red channel was used.  IRIS pre-processing almost all automated with AutoIt scripts. Curve stretching in Photoshop CS.  Background gradient removal in IRIS. Noise reduction in Neat Image.

Comments

Acquisition was managed by GADFly, an AutoIt script I wrote to automatically nudge the position of the guidestar every few exposures.  This is done to avoid noise pattern build-up in the sky background.  In this case, some pattern did appear in the background - probably did not move the guidestar enough during the exposures.

 

 
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