|"When I consider your heavens, the work of your fingers, the moon and the stars which You have set in place, what is Man that You are mindful of him?" -- Psalm 8:3,4|
Analyses of Homemade GEM1 Guiding System
Finally I had chance to test my homemade GEM1 guiding system. Although seeing conditions were not very good (soft wind), I could not resist an opportunity. I put my Philips Vesta 675SC2 webcam at prime focus of my 8" F6 Newtonian. The resolution of such system is 0.96arcsec/pixel. I selected Altair as guiding star:
Here are results of my tests. Click the pictures to
see full sized pictures.
The second thing, which I decided to measure, was
effect of guiding on result photograph. I captured 2 AVI
files of Altair with 40 and 120 short exposures (with
period of 1s) and summed the frames to simulate long
exposure. It represents long exposures of 40s and 120s.
The PSF (Point Spread Function) was measured for both raw
and summed frames. Here you can see the results:
The following table shows differences between raw frames, summed frames (simulation of long exposure) and summed aligned frames (simulation of long exposure with perfect guiding).
Conclusion: Although the guiding system is not perfect, it offers long exposure star image with FWHM only by 1.3 pixel worse than aligned summed image.
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Last Update: 22.09.2002