John Upton


   I have a question about Roland's Quick Star Drift Alignment Method as documented in the Mack2 User manual. (Appendix C on Page 41.) I tried it out the other night and all seemed to go pretty well. The Azimuth Alignment step went perfectly and was easy to perform. I did use a shortcut of sorts by simply doing a Plate Solve and Recal just West of the Zenith before slewing to a star in the south just West of the meridian.

   My main question is whether (or how much) this method depends on having previously corrected for any Orthogonality / Cone Error of the OTA. I had quite a bit of East / West offset difference when I performed the second stage of the method to dial in the Altitude adjustment. I was surprised at how much I have to change the Altitude axis (nearly a full turn of the Altitude adjuster) to move the star N/S to get back to the crosshair. I had started by using the Park 5 / Level OTA initial adjustment before beginning this method.  Any idea why the Altitude had to change considerably after leveling in Park 5? (I  pretty much trust the Level since I have calibrated it carefully and get exactly the same repeatable reading when turning it 180° with less that 0.05° reading difference.)

   So, back the main question; does this method work equally well even in the presence of orthogonality error? I really like the method as it is very , very fast but wonder about the E/W star offsets I see when adjusting the altitude of the RA axis in the second half of the procedure.


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