Re: Mach1 Unable to Find Home Position Suddenly


Ray Gralak
 

Hi Mikko,

Well it seems that "park from the last position" was the cure and yesterday evening the Mount slewed were it was
supposed to and plate solved the first image in seconds as before this whole episode started. I would still like to
understand what has changed and why suddenly unpark from #3 is not working anymore. Does the success of
unparking from the last position tell us anything? Meanwhile when smarter people than I are pondering this, I
want to thank everyone who participated to this conversation and proposed different things to try or consider.
After you recal/sync the mount via a platesolve and return to one of the park positions it can appear to be in the wrong position under certain conditions such as:

* The pier/tripod is not perpendicular to the earth's center.
* The mount is not "perfectly" polar aligned
* The optical axis is not aligned with the mount's mechanical axis.

So thinking the mount was in the wrong position one might be tempted to "fix" the mount be loosening the clutches and putting the mount back in the "correct" position then unparking from that park position. Doing that will actually cause the mount to be in the wrong position.

By just resuming from last parked position the mount should be exactly where it left off when last park. In fact both the AP V2 driver and APCC should warn you that it will set "unpark to last position" when you try to unpark from one of the park positions. That's to prevent people from making a mistake and accidentally unparking from the wrong park position. You should always use "unpark from last park position" if you have not moved/declutched the mount/scope since the last time you parked it. Of course if you are setting up the mount in a new location, or declutched and manually moved the scope to a new park position, it is appropriate to unpark from one of the park positions to start off.

BTW, this implies the mount is not a Mach 2. Since the Mach 2 always knows it's RA/Dec mechanical orientation you can only "unpark from last park position". :-)

-Ray Gralak
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Mikko Viljamaa
Sent: Sunday, March 22, 2020 5:36 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Mach1 Unable to Find Home Position Suddenly

Well it seems that "park from the last position" was the cure and yesterday evening the Mount slewed were it was
supposed to and plate solved the first image in seconds as before this whole episode started. I would still like to
understand what has changed and why suddenly unpark from #3 is not working anymore. Does the success of
unparking from the last position tell us anything? Meanwhile when smarter people than I are pondering this, I
want to thank everyone who participated to this conversation and proposed different things to try or consider.


Thanks,

Mikko

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