Re: Erratic parking of the mount

Christopher Erickson

One of my personal rules is that I never recalibrate or sync any GOTO mount on solar system objects. The orbital calcs are always complex and positional errors are the rule, not the exception.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738

On Thu, Feb 13, 2020, 8:20 AM Donald Rudny <mkea13800@...> wrote:
Hi Bruce,

Just saw this and agree that it’s probably your re-aligning or recal when you are in different parts of the sky.  I noticed that even when I use APCC to initiate.  When I would start another session and pick start from position 3, alignment was off.  What I needed to pick was “last parked”.  I could see from the marks on the axes that the park 3 position was off a little.  Once I used last park, it worked perfectly.

Unfortunately, SkySafari has limited choices for initiating and unparking.  You would need to reset your park 4 position each new session unless you didn’t re-align during the prior one.  One thing you could try is to realign on a star near the park 4 position before you shut down.  That would be low in the southern sky.  That should at least get the next startup closer.

Don Rudny

On Feb 13, 2020, at 7:54 AM, Bruce Donzanti <donza2735@...> wrote:

Great- good to understand what is probably causing this and that a solution is forthcoming.  

Thank you 

On Feb 13, 2020, at 12:05 PM, uncarollo2 <chris1011@...> via Groups.Io <> wrote:

Usually, this is fine but every now and then I noticed the scope does not park in position 4 exactly as it should (i.e., the RA axis is slightly off level).
All sky positions are calculated from the previous object that you did a Recal on. That includes park positions. If the last object that you Recal on is off by 1 degree when you pressed Recal, then every object that you go to including all park positions will also have that 1 degree error.

Your errant Recal could be the result of an error on your part or deliberate if you wanted to center a nebulous object and then did a recal on it. What you might think was the center might not be the center as defined in the database, so that throws off everything else following that move.

We are working on changing the way parks are generated so that they are not affected by errant recals or syncs. The software will be available for the CP4 and will be standard in the Mach2 CP5 controllers.


-----Original Message-----
From: Bruce Donzanti <donza2735@...>
To: main <>
Sent: Thu, Feb 13, 2020 5:42 am
Subject: [ap-gto] Erratic parking of the mount

In my permanent setup,  I use SkySafari 6 Pro as my planetarium program to slew my AP1100 with no issues (connected to the GTOCP4 via RS232).  It parks and unparks from position 4 with no issues.  I also use PHD2 for guiding by linking it as required to the mount to my capture and live viewing software (SGPro or SharpCap) which are connected to mount via USB with no issues.  However, I have had random problems with shutting down the system.  I first park the scope using SkySafari 6 Pro and then close PHD2 followed by the capture software.  Usually, this is fine but every now and then I noticed the scope does not park in position 4 exactly as it should (i.e., the RA axis is slightly off level).  I can't seem to figure out what is the cause as it is very infrequent but annoying as it misaligns the scope for the next time I startup Skysafari 6 Pro to slew to an object (i.e., the mount is lost and I need to realign).  Any thoughts as to what is going on?  Is my shutdown sequence wrong?


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