APPM for single target #APCC #Mach2GTO

David Johnson

Just received my Mach2 and very happy with it. Until I get a permanent setup, I set up and break down my system just about every time I use it. I have APPM working, but I was thinking last night that since I tend to have one imaging target all night, I really don’t need a model for the whole sky and should be able to save considerable time by densely modeling just along the declination of the target. Can I please get some tips for using APPM for this kind of situation?  Thanks. 



There have been posts in the post showing that building a model along the declinaton of the single object works well.  See lengthy thread at

In addition, Ray Gralak is working on an upgrade to APPC Pro that will include declination-arc tracking that is very accurate.  I defer to Ray for further info on timing for this.


David Johnson

Thanks for the info. My concern is what would happen outside the modeled area. As someone who has done models myself in a different area, I just want to make sure there are not extrapolation errors outside the modeled area. I might need to slew to those areas for some reason. Bottom line is I assume the correction is zero outside the modeled area?

Richard Schiek

I'm in the same boat.  I don't have a permanent setup so I haven't used APPM as I had hoped.  But being able to build a model around a given object or point the in sky would be very useful to me if it improves tracking accuracy. 


David Johnson

What I’m going to try tonight if I don’t hear anything is the following. My target’s declination is about  +13 degrees.  I plan to densely map points from +10 to +20 Dec all across the sky. 

Dean Jacobsen

I have had excellent results with doing two and three line APPM map runs which bracket the declination of the target for the night. 

There was a discussion on this last summer -,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,600,74888714
Dean Jacobsen
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David Johnson

Thanks. I’m going to try it tonight. 

David Johnson

Here’s what I did.  Seems to work fine.