The Moon occults Saturn Dec. 9th 1997

    On december 8/9th 1997 the moon occulted saturn. The disappearance took place on the dark limb and provided for a nice series of cut through pictures for saturn. The sequence of pictures was taken with an 8 inch f10 schmidt-cassegrain. To increase the image scale to allow saturn to be better resolved a 2x teleconverter was used. For the choice of film a compromise has to be made between exposure time and graininess of the film. The film chosen was Kodak Elite 100 slide film. To avoid vibrations from shutter operation and the rapid winding of the camera to interfere with the pictures a very stable equatorial mounting was used. At 100ASA the exposure required for saturn in the described setup was about 1/4 second. Longer exposures saturated the image of the moon too much. Saturn being much further from the sun than the moon receives much less light per area and thus is much fainter in surface brightness. Luckily its high albedo (reflectivity) vs a rather dark surface of the moon compensates a little for this effect. Nevertheless at 1/4 second saturn still is about 1 stop underexposed whereas the moon is already close to saturation in the brighter portions. The resulting slides were then transferred onto photoCD. For further processing the 1500x1000 version of the photoCD image was used. To compensate for varying exposure times all images were brought to similar brightness levels and saturn was cut out into smaller pictures from pictures as those shown below. Click on the picture to see a 500 x 500 pixel image.
    These are the cut out pictures of saturn slowly being occulted by the moon. The varying seeing quality resulted in the differences in definition in the images.

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