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M83, in Hydra.  An intermediate spiral/barred type galaxy, sometimes known as the 'Southern Pinwheel'.  Located about 15 mln light years away.

 

Comments

Telescope:  Skywatcher 8" f/5 Newtonian

Focus:  Prime focus

Camera:  SAC7B, uncooled

Exposure:  93 x 25s 

Date:  3rd May 2003

Processing:  Acquired in K3CCDTools as AVI.  Stacked in Iris.  YRGB image, composited in Photoshop.  Colour enhanced using Multiple Luminance Layering.

Comments

Processed using the YRGB technique.  During the later stages of curve stretching in Photoshop the brighter stars were prevented from bloating by de-selecting them.  Artifacts from this are mostly not apparent except for the pair of stars at the bottom right just above the caption, where some halo is visible.

Some of the characteristic diagonal banding noise from the SAC7 camera is visible in the brighter regions just outside the galaxy core.  In this case no wavelet processing was applied to reduce this noise as it wasn't too bad.

The image has some colour information, but star colours are mostly not apparent.  Also the red colour in regions of nebulosity in the arms of the galaxy did not appear.  Perhaps I could have done more to increase colour saturation.

Unsharp masking usually results in stars getting unpleasantly sharp with a dark ring in extreme cases.  In this image the bright stars were de-selected in Photoshop (using the Magic Wand), and unsharp masking was applied to the rest of the image.  The selection was then inversed and so gaussian blurring was applied to soften out the star images.

Full details in the Image Processing section.

   
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