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The Globular Cluster Omega Centauri (NGC 5139).

This is probably the most massive globular cluster in our galaxy, with about 10 million stars.  It is about 150 light yrs across and about 15,000 light yrs away.


Image info

Telescope:  Celestron 9.25" Schmidt-Cassegrain at f/6.3

Focus:  Prime focus

Filter:  None

Mount:  Vixen GPD with Skysensor2000

Camera:  Modified Canon EOS 300D, at ISO400

Guiding:  700mm, x2 refractor guidescope, SAC7 camera, autoguided with Guidedog software

Exposure:  Total 37 mins (37 x 60s)

Date:  11th April 2005

Processing:  RAW file conversion, Offset and Dark subtraction, flat fielding, registering and stacking done in IRIS.  Only the Green channel was used and converted to monochrome.  Curve stretching and a little unsharp masking in Photoshop CS.


I found out during processing that the flat fields I had taken that night were accidentally in JPG mode (rather than RAW) and worse, was a different size.  Attempts normalise the flat field failed, so a good colour image could not be produced.  Hence the monochrome image, which minimises the visibility of the flat fielding problem!


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