Re: MACH2GTO Home Position #Absolute_Encoders #Mach2GTO

Roland Christen

Home sends the mount to the Park3 position, then re-calibrates the mount and wipes out any small centering adjustments that you made when you slewed to your first star and recal'd on that star. Home will go to the Park3 position, but then resume tracking at sidereal rate. Remember, "Home" is for getting the mount back to a basic start position which assumes absolute perfect polar alignment. Of course you will never have perfect polar alignment so your first slew will always be off by that amount, so that's why you do a recal. I know it may seem counter-intuitive, but in real life nothing is ever perfect. Home is also for wiping out any errant recals/syncs that you may have done and gotten the underlying star map out of alignment with the real sky. In other words it gets you "unlost" if you told the mount that Vega was Betelgeuse and sync'd on it erroneously.

Park3 sends the mount to that park position, and when it gets there it simply un-powers the motors and stops tracking. It does not wipe out any small centering corrections that you made during your session. For the next session, simply resume from present position (do not use "resume from Parkx" with a Mach2 encoder mount).

You don't have to have your Mach2 mount in any of the park positions when you resume the next operation. You don't have to park the mount in any of the park positions when finishing a session. You can leave it anywhere and just turn off power. You can start it pointing to China if you want, after parking the last session pointing to the Moon. Makes zero difference in the Mach2.


-----Original Message-----
From: Eric Weiner <weinere@...>
Sent: Sun, Feb 28, 2021 1:08 pm
Subject: [ap-gto] MACH2GTO Home Position #Mach2GTO #Absolute_Encoders


First off, love the MACH2GTO-L. What an amazing piece of engineering and precision machining. Kudos to your engineers and machinists. 
The manual discusses the home position as, “... a very special position that is established by Astro-Physics when programming the Absolute Encoders. It is highly precise.”

Are you able to share a more technical discussion regarding the home position?

Is there any reason why I shouldn’t use the home position in lieu if park 3?
My apologies if this has been discussed before. I’m new to the style of forum. 


Roland Christen

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