Re: Ap900gto parking issue at end of the session

Dale Ghent

On Jan 21, 2023, at 16:06, palamrinder via <palamrinder@...> wrote:

Hi Dale
So I followed your instructions. The first and second item checked out. All settings were as you described. I manually moved the scope towards zenith and tried plate solving. But even though plenty of stars were visible ASTAP failed to plate solve so the backup astrometry option kicked in. It took some time for it to plate solve but right after plate solving the mount starting moving counterclockwise and I had to manually stop it to prevent scope going upside down (see second picture).
I manually put it back in park 3 position and defined it in ASCOM. Plate solving worked flawlessly after that. Also in the sequencer I selected centering as an option. The scope this morning ended up close to Park 4 position which is different from previous nights.
I suggested plate solving in the eastern or western sky with the intent to imply that plate solving at zenith, on or near the meridian, is not necessary. Because I can't see how you've actually go about doing this, I at least wanted to be sure that you were doing the solve with the counterweights down, below the horizontal axis of the RA.

As for the initial plate solve failure, is this a common occurrence? There is a consideration here, as with your SCT, you'll want to be certain that you're using the correct star database in ASTAP. You'll want to be sure you've downloaded and installed (and set ASTAP to use) the H18 star database, as your SCT's FOV will be in the range where the smaller H17 database may be insufficient. If you are running with the H17 database, uninstall it and install the H18 one. Open up ASTAP and go to the Alignment tab to ensure it is set to either Auto or H18 for the database to use. While you're at it, ensure you've installed the current version of ASTAP itself.

The solve alone should set your mount straight provided it has accurate time and counterwieghts are down. Your earlier screenshot of your coordinates looks fine for someone in North American (N of equator, W of the prime meridian.) So something else is going on here and, since it's the park function which is completely controlled by the mount, it's something either in your settings or in your methodology that is getting things literally turned around.

When you manually drive the mount to the Park 3 position (counterweight bar straight down, scope looking at the celestial pole), you should do the following:

1. Manually drive the mount to Park 3 using the N/E/S/W buttons in the ASCOM driver's UI. Get it close, but it doesn't need to be painfully exact.

2. In the ASCOM driver's UI, hit the Expand button and set the Park Position to Current position, then press the Park button. The mount should park right there without moving anywhere.

3. Then, set the Unpark location to "Park 3" and unpark the mount. The mount should then unpark and start tracking (or not, if you have don't track on unpark turned on)

4. Reset the Park position setting to "Park 3" an the Unpark position setting to "Current Location"

5. Drive the mount around a little bit using the N/E/S/W buttons in the UI. You don't need to drive it far off the Park 3 position, just appreciably so. When you're done, press the Park button. The mount should go back to the Park 3 position and park there. If it doesn't do this and goes off in some wild direction, something is seriously weird.

For extra bonus, ensure that the RA and Dec motor cables are not swapped, and that the N-S switch on the CP3 lower right corner is not set to S ;)


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