Selenology Today # 7 July 2007 - Home

Fig. 2
OCCULTATION SELENOLOGY TODAY # 7
A next photomontage (Fig. 3) has been generated based on two images of the eastern
lunar limb and of Saturn which were acquired subsequently. This procedure was
necessary to cover the extremely high dynamic range of the scene, since the surface
brightness of Saturn is much lower than that of the Moon. The relative position of the
Moon and Saturn is metrically correct; it was determined based on structures visible at
the lunar limb in the original video images.
The Lumenera LU075M camera was run at 15 frames per second. For stacking the video
frames, the free software Giotto (http://www.videoastronomy.org) was used. As a
highpass filter, the Giotto Gaussian/Rectangular filter was employed with filter sizes of
9x9 pixels for the Gaussian component and 7x7 pixels for the rectangular component.
The filter strength was set to a value of 180. To reduce the brightness of the twilight sky,
a Schott G 495 yellow filter was used.
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