Re: APPM model how many points portable?

My 1100 is due this summer so very curious also, as I will set up each night and tear down, often with a C11, sometimes a 4” refractor.


Right now with a MyT I do one large model, then a recalibration each night which takes 10 minutes.  I understand that’s not exactly possible with the AP mount.

One thing from the MyT experience and an SCT – unless you have the mirror locked, the point of diminishing returns gets reached fairly quickly in terms of number of model points and increasing accuracy, as with mirror movement there is an inherent lack of repeatability of getting back to any area of the sky.  Getting a model that gets fractional arc second precision with a scope that’s not repeatable except maybe to 5” or more is not very useful.   One day I may get a different focuser and lock my mirror but in the meantime I accept that lack of precision.


But spending 90 minutes a night building a model will be a real bummer.   Is it a plate solve issue?   TSX only takes a second per image to solve.  I really do not like TSX in general, and glad to be getting away, but… 90 minutes?  


Say it ain’t so!




From: [] On Behalf Of Roger Howard via
Sent: Sunday, April 11, 2021 5:59 PM
Subject: [ap-gto] APPM model how many points portable?


Hello, looking for opinions and guidance for how many points to model.  There are a lot of topics on this but none of them seem to answer my questions.  I set up each time in my backyard in the same place on an ATS portable pier.  I'm using APCC Pro, 1100GTO, Edge 9.25 with OAG and SGP.  My pier is within I would estimate the same few inch square each time its set up. I did a 93 point model last time because I knew I would have several nights to image and it worked great.  The problem is that with a couple failed points that went to all sky solve it took well over an hour and a half using SGP and platesolve 2 as my plate solver.

My question is:  Just use the 93 point model since its almost in the same spot?  If not, how many points to model when I will be guiding?  My problem is that summertime dark isn't until about 8pm, and I get up for work at an early 0345 every day, so if I want to just do a night or two when the sky is clear for just a night or two, what should I do?  Is there a minimum number of points?  Can't dedicate a couple hours to get a pointing model because I have to hit the sack early (ish).  I know an observatory would be the answer, but in my yard that isn't happening.  Thanks for your experience.


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