#### Re: Question: ROLAND’S GTO QUICK STAR DRIFT METHOD - 2020 VERSION

Roland Christen

First question; Yes it works even with horrible orthogonality.

Any idea why the Altitude had to change considerably after leveling in Park 5?
This question is quite easy: The parks are governed by the time you have set in the keypad (or your laptop). If you are off by 1 hour, the parks will be off by 15 degrees in RA. For every second that you are off, your park positions will be off by 15 arc seconds.

This is also a way to check your exact local time - simply change the time in the keypad by a minute or so (or even a few seconds) and park again until your park position is exactly parallel to the earth. Presto, you have now synchronized your time to the stars.

Rolando

-----Original Message-----
From: John Upton <upton@...>
To: main@ap-gto.groups.io
Sent: Mon, Sep 13, 2021 3:22 pm
Subject: [ap-gto] Question: ROLAND’S GTO QUICK STAR DRIFT METHOD - 2020 VERSION

Hi,

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.

John

--
Roland Christen
Astro-Physics

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