Re: Trouble with MaxDome II slaving to APPM

Shane Ramotowski

Hi Alan,

I ran into this a few months ago.  AAPM does not have a way to do dome geometry so it's dome positioning command are wrong.  They are all based from the center of the dome instead of where the telescope is.  You've seen the first dome slew; the rest are incorrect also most end up with the dome partially or totally occluding the scope.

There is an extended topic about this from February: <>

According to Ray, there are no plans to fix APPM's "Active" mode as he believes that dome geometry should be built into the dome driver.  But it's not.  ASCOM standards do not include dome geometry, nor the ability for the low level drivers (dome and telescope) to exchange information and send commands to each other. Every other application I've used that claims to do dome/mount slaving/coordination implements dome geometry.

I don't really know why there is an "Active" mode--I guess if you have a really small scope or a really wide dome slot, it might work.  But my scope is a 4 inches and the doe slot is 18 inches wide and I still can't use it.

You can use the "Passive"mode (in "AP Point Mapper -> Dome Settings" and ASCOM's Device Hub or SGP's Dome Slaving, but you will likely have to add significant delays so that APPM can recognize that the dome is moving .  The big disadvantage of this is that your mapping settings will take hours--I guess that's OK since you shouldn't need to do them that often...

The good news is that both Device Hub and SGP are smart enough to slew the dome to the correct position, even when the mount goes counterweight up!

Good Luck - Shane

On 9/19/2021 4:47 PM, wrote:
Hi. I'm trying to run APPM with MaxDome II. The first image attempt at the zenith fails due to the dome being 180 degrees off. The scope is on the west side of the mount / counterweights on the east. The dome shutter azimuth is east, but it really should be west because that's where the scope is. Image attached. Any ideas?


Shane Ramotowski

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