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Satellite Passes

Below are a few animated GIFs of captured footage by Greg Roberts' VIDEOTRAK system under computer control of the CoSaTrak Computerised Satellite Tracking software by Willie Koorts.

The original footage was recorded to VHS tape, directly from the output of Greg's low-light surveillance CCD camera, fitted with a 150mm f/2.8 TV camera lens driven by his motorised mount. Frames were then grabbed using a Snappy video capturing device, reduced in size to 320 x 240, some were rotated through 90° (the true orientation) and finally combined into animated GIFs. To show the relative movement, only footage showing some background stars were selected. This reduced the possibilities somewhat, since Greg's system has a field of view of only 1.9 x 1.4 degrees, can see down to about magnitude +7 and the faint stars are lost in the reproduction.

These GIF images can only give a rough idea of the real performance of the system because of big losses introduced in the recording, digitisation and image scale reduction processes to produce these animations. To reduce filesize, frames were reduced to 320x240 and grabbed at about ½-second intervals, resulting in some "jerkiness".


Greg later upgraded to a more sensitive surveillance camera capable of 0.01 lux. This he fitted to a 135mm focal length f/3.5 still-camera lens to shoot these pictures.

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