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Subject: Re: Meade DB Accuracy Workaround
From: Howard Anderson
Reply To: mapug@shore.net
Date: Fri May 12 08:56:52 1995
> I enjoyed the Ralph Pass post regarding a new accuracy
> workaround, but it did generate a few questions for me.
> First, steps 5 and 7 requests a double 'GOTO' push. Its not
> obvious to me the purpose of this step. I'm running 2.4,
> and I believe the second GOTO would effectively do nothing
> on my scope.
Cannot speak for your scope and version of software but in the workaround I published some time ago on this list, I indicated that I had to do a double 'GOTO' to get the scope to finally settle on the correct value. The first 'GOTO' got the scope relatively close but the second one caused a tiny bit more motion that was closer to the requested value. Subsequent 'GOTO's did not alter the scope's position further. The position readout on the controller does show the effect of the first and second 'GOTO' so I can see that the second does actually produce a correction. I would have believed the "second GOTO would effectively do nothing" before I attempted my alignment workaround but I found that it *did* do something.
Ralph's workaround is an improvement over the one I posted earlier because he uses the SAO catalog's coordinate values of the 33 alignment stars. The SAO catalog coordinates are apparently more accurate than the coordinates that were stored in the 33 alignment star list. Being a software guy, I had assumed that the 33 alignment star list coordinates would be linked to the SAO catalog coordinates but they are apparently stored separately and have different values? I have not had a chance to check all this out yet but it begins to sound reasonable...
The problem with the other workaround that you mentioned regarding getting coordinates from another source in my opinion would not work because you need to use the scope's SYNC process to cause the software to match the coordinates of an object selected from the scope's database. It knows what you selected and it knows what it thinks the coordinates of that object are. It will sync with respect to those coordinates and not to any external coordinates.
Thanks
Howard