Re: Home index for AP mounts?

Wiggins, Rick

Hi Joe,
I will explain and maybe later post pictures...I need to find them to post, so it will happen whenever I find them.

I placed a thin metal strip between two of the RA thumbscrews (remove and place the stip behind). Before placing the stip, I had measured and drilled a hole to allow the placement of a rubber shaft (approximately 3/4 inch raised from surface of RA drum and 1/4 inch dia)in the middle of the metal strip such that it crosses the center of the pier on the side nearest the floor at the same time the scope is pointed exactly at the horizon plus about 2 degrees.

I then attached a small microswitch to a flexible metal piece which was in turn attached to the pier and allowed the microswitch to stick up where it would be hit squarely when the rubber shaft crossed the center of the pier.

The microswitch drives a relay that turns power off to the mount. The relay is powered by a network switch that I can control over Internet.

How it works: When the scope slews down to the horizon as does not flip (i.e. software is hung up, etc.), the relay is opened and power to the mount is turned off. When I notice the problem (usually the next morning), I turn off the master power to the mount (upstream from the relay cutoff)...power remins off to the mount. Now I turn off power to the relay (Internet control again). I then turn the master mount power back on. At this point, the mount resumes tracking as the relay is disabled. Very quickly, I use the motion controls in TheSky to nudge the mount back above the horizon. Now I have regained control of the mount/scope in a known configuration (i.e. the mount knows where it is and is not considered "under the mount"). I then turn the power to the relay back on which enables my protection again. Finally I park the mount. When I restart the mount it is still in "Sync" and will slew as directed.

Hope this helps,

--- In, "jmorris6966" <joemorris@...> wrote:

Hi Rick -- Could you explain a little more about the micro switch, ie
part #, installation, pictures?


--- In, "Rick" <rickwiggins@> wrote:

Hi Dave,
I have used AP mounts in remote robotic observatories for 5 years. They can get lost...usually due to software glitches with programs other than the AP. There are several things you can do.

I added a microswitch to stop the AP mount if it slews West past the horizon. When this happens, and I find it the next morning, I then turn off power to the mount, turn off power to the cuttoff microswitch, turn power back on to the mount, and slowly bump it back to above the horizon using TheSky Motion controls. After that, you can continue to slew because the AP will not lose its position unless it hits the pier (which was prevented by the microswitch).

The SkySolve program mentioned by one of the other members also works and I have used it to recover position.

Install red lights and a good IP Camera in your dome. Position the domw slot to a known position with a known large bright sky object (the moon works best, then Jupiter, then large nebulas). THen manually slew the scope to point out the slot and run SkySolve.

I have manually realigned the scope without SkySolve, but it can take hours.

I have done these things and they work. DOn't give up on the AP mount just because it does not have a stop.

Good luck,

--- In, "mogulskier_groups" <mogulskier_groups@> wrote:

For various reasons, sometimes the AP1200 mount gets lost. It often happens when the camera has bumped into the pier or after the mount has been tracking the camera against the pier for several hours because I fell asleep. It's easy enough to fix by going out to the scope, giving it a park command, using a level to adjust the scope in ALT/AZ, but...

For those of you using AP mounts in remote observatories, how do you remotely re-orient the mount when this happens? Whenever I attempt to do this remotely, it takes a lot of time and effort and I finally give in and go out to the mount.

Some mounts, like the Paramount ME, have an "index". Is that some kind of index for the home position? Is there anything available like that for the AP mounts? I've seen "limit switched" deployed on AP mounts, but I don't want to cut power to the entire mount and I wouldn't know how to re-energize the circuit.



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