APPM with Dome Questions

Shane Ramotowski

Hi gang,

I am the proud owner of a brand new (well 2 weeks) Mach2 and tried to do my first APPM model tonight.  I'm having problems with the dome control and hope someone can point in the right direction.

My observatory is a ClearSkys (I don't think they are around anymore) 8 ft dome.  The pier is centered and the bottom of the mount is just about even with the bottom of the dome.  The rotation control is homemade (my COVID quarantine project) and works very will with both ASCOM DeviceHub and SGP.  I'm using SGP for image capture and plate solve.

I can't figure out how to set up APPM to control the dome properly. If I use "Active" in the "AP Point Mapper - Dome Settings" panel, APPM seems to do it's calculations based on the center of the dome instead of where the telescope is.  This is not surprising since I can't seem to find any where in the program or the documentation to set the mount and telescope geometry.  I suppose, since APCC knows that I'm using a Mach2, it _could_ already know roughly how far from the center of the RA/DEC axes intersection the bottom of my telescope is.  But I don't see anyway that it could know where the center of my OTA is.  I really don't think it's using the parameters from 3D view; I haven't set that up, but the default is a much larger diameter telescope than mine.

 Anyway, when I use "Active", I end up imaging across the edge of the slot because the slot is positioned for the center of the mount instead of where the telescope is.  Most of the images ended up plate solving anyway, but since  the stars are all diffraction spikes, I don't know the quality of those solutions.  The initial slew to meridian is probably the worst because the dome is in the exact opposite position than it should be and my slot just goes barely past vertical.   I checked the ASCOM logs on the PC and my ASCOM debug screen on the dome controller.  The dome _is_ slewing to the position that APPM requests; that position just doesn't seem to be based on where the telescope is.

Can anyone tell me what I'm missing?  Where do I enter the offsets for the mount/scope geometer so that APPM can got to the correct position?

So, after trying "Active", I swiched to "Passive" and tried with two different dome slaving programs: ASCOM Device Hub and SGP.  For "Delay before starting dome slew checking", I used values ranging from 5 to 30 seconds.  For "Settle time after dome stops slewing", I used values from 1 to 20 seconds.  I didn't see any effect when changing these settings; in all cases the the telescope slewed to the next position and started imaging a few seconds after it got there--many seconds before the dome was in position.  None of those images solved since the dome was in the way.  Again, I can't figure out what I'm doing wrong--it's like I'm not even changing the values.  Is there another setting that I'm missing that enables these timeouts?

I'm sure someone else has successfully done an APPM run from an automated dome!  What am I missing?

Thanks - Shane

Shane Ramotowski

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