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The Dumbell Nebula, a planetary nebula in Vulpecula.  M27 is a bubble of gas that has been ejected by a star at the end if its life. This star is visible in this image at the centre of the nebula - at the point where the red parts of the nebula appear to meet.  The gas bubble glows because of UV light from this star. M27 is estimated to be only 3,500 years old and about 1,000 light years away.


Image info

Telescope:  Skywatcher 8" f/5 Newtonian

Focus:  Prime focus

Camera:  SAC7B, uncooled

Exposure:  77 x 25s 

Date:  19th July 2003

Processing:  The usual YRGB processing, except that the subtraction of a 'banding flat' (see the Advanced Processing page) was done to remove fine banding noise.  Noise reduction in SGBNR on the final colour image.  There was a slight brightness gradient from left to right in the raw images, so subtraction of a synthetic sky background image was done in Iris.


Sky conditions had been rotten for a month and a half at the time this image was made.  On this night conditions started out at medium transparency and deteriorated after less than an hour.  I kept the telescope tracking this object for 3 hrs.  Out of more than 400 frames taken, only 77 were usable. The new technique to remove fine banding was very necessary here due to the low surface brightness of the object.

Luminance layering was done to increase colour saturation.


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