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Helix  Nebula,  NGC  7293,  In  Aquarius

     The Helix nebula is another planetary nebula, and consists largely of hydrogen gas and other substances thrown off by an exploding star. Although quite large, it is rather dim and low on the southern horizon at my site in California so it is one of the more difficult nebulas to image. For some reason, I chose two nights with an almost full moon, which compounded the difficulty. By imaging the luminance layer in hydrogen-alpha light, I was able to reduce the effect of the moon.

 Date

 2003 October 10, 11

 Scope

 RCOS Ritchey-Chretien with two A-P reducers: 0.75x and 0.67x for a final focal ratio of

  approximately 4.5. All mounted on an A-P 1200GTO mount. Guiding with separate 900 mm

  focal length guidescope and SBIG ST-4 guider.  Camera: SBIG ST-10XME and CFW color

  wheel, controlled with MaxIm DL/CCD, v 3.1.

 Exposure

 R, G, and B exposures 5 x 5 min, 1x1 binning plus 5 x 5 min, 2x2 binning. Six x 5 min H-alpha

  frames, binned 1x1, were used as the luminance layer.

 Processing  

 Frames flat- and dark-calibrated and RGB combined in MaxIm. The luminance layer was

  registered with the RGB composite in RegiStar and then combined in Photoshop.  Final

  processing with Levels  and Curves in Photoshop.

 

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