Handbook for SXV-M5 Issue 1 June 2004
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shots are usually about half the height of the CCD frame and I find that the ‘radius 5,
power 5’ values are good for most average seeing conditions. If you have
exceptionally good conditions, then a reduction to R=3, P=3 will probably give a
more natural look to the image, as too large a radius and power tends to outline edges
with dark or bright borders.
As a finishing touch, the application of a Median filter or a Weighted Mean Low Pass
filter can be useful to smooth out the high frequency noise after a strong Unsharp
Mask.
As with deep-sky images, it is advantageous to sum planetary images together to
improve the signal to noise ratio. In this case, the ‘averaging’ option should always be
used, or the result is likely to exceed the dynamic range of the software and saturate
the highlights. Aligning the images is always something of a problem, as there are
rarely any stars to use when imaging the planets, but Jupiter’s satellites can be useful
reference points. Otherwise, you will have to find a well-defined feature on the planet,
or estimate where the centre of the disk is located. Some more sophisticated software
can automatically align planetary images, but I do not find it especially difficult to do
by eye.
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Other features of SXV_M5
‘Slew & Sum’ imaging:
The SXV-M5 can be used in an automatic image-stacking mode, called ‘Slew &
Sum’. The camera is set to take several sequential exposures, which are automatically
‘slewed’ into alignment and then summed together by the software. This mode can
help to overcome a poor RA drive by summing images that have exposure times
shorter than the drive error period. The resulting image has more noise than a single
exposure of the same total length, but this method of imaging is still an effective way
of making long exposures.
