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PE measurement for my GM-8 Using Albireo and Dec Scan


Sep 11, 2003

 


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#43446 Jul 26, 2009

I'm looking for feedback from other Losmandy users on a technique I tried last night to measure the PE, uncorrected and corrected, of my GM-8 mount. Becaue I do not have autoguiding at this time, and no computer attached to the mount, I used a DEC scan at 0.5x (1-degree movement per 8-minutes) while photographing Albireo at high power (approx 300x) with open shutter. This produces a straight line in declination, with RA PE showing up as wobble in the lines. Because Albireo will produce two distinct lines separated by 35", I can see how the PE compares to this "measuring stick". I then overlaid the images in Photoshop for closer evaluation of the corrected vs. uncorrected scans.



With this technique I estimate the PE at about 14" uncorrected. After training the drive with PEC, it is about 5-6".



I've posted a composite photo in my album, showing 2 reps of the uncorrected scan, and one of the corrected, spanning about 4 minutes of the eight total.



Thanks in advance for any input each of you might have.



Ron



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