Mount Run-Away During Centering

I am using a trial version of SGP (version 2.6.0.23). I cannot seem to get SGP to recal my AP mount via centering with a plate solver. Two nights in row now the mount has “taken off” during an attempt at centering.

I used the AP driver to reach the approximate location of M 104. The mount read RA = 12 40 01, Dec = -11 37 35. I started SGP, loaded my M 104C sequence, and used frame and focus to take one 10-sec image. Before starting SGP I focused the telescope using focus max, so stars were sharp and easily visible. I right-clicked on the SGP image and selected plate solve, giving my first guess as the actual coordinates of M 104 (RA 12 39 59.2, Dec -11 37 23), and scale 1.67. My local version of Astrometry.net plate solver worked quickly and accurately, showing that the center of my frame was actually RA = 12 43 03, Dec = -11 23 32. Note: M 104 was nowhere to be seen in this frame!

Next I went to target settings and entered M104’s actual coordinates (see above) and clicked the center now button. SGP went into its centering mode, taking an image and saying that the frame was off thousands of pixels in each dimension. It then attempted a move (I think) and took another image (I think). Same result - thousands of pixels off. On its third attempt the mount took off. Two nights ago I aborted immediately. Last night I let it go to see where it was headed. Weights swung vertical, then past vertical a bit, then reversed direction for a second (all RA motion). This looks scary with the telescope near the floor! Then Dec took off, unfortunately in the wrong direction - the scope was going to hit the pier. So I aborted, got out of SGP, and saved the log file.

Can you tell me what’s going wrong? Driver error on my part? After the abort, mount coordinates were way off, apparently reset incorrectly by SGP.

@mjpost

I can’t tell you for sure what was going on but it sounds like your mount was not initially sync’d to the sky. I don’t know if you are new to AP mounts but one issue is that you basically can’t use both the handbox and a computer to control the mount at the same time. The handbox stores its own “where am i” info and if the mount is moved with the computer, the handbox won’t know it and a run away slew can result.

Having said that, a good start up procedure with SGP and an AP mount is to use the ASCOM interface to slew the scope to a point on the meridian near the equator. Then perform an autofocus (or manual focus). Now click the “solve and sync” button. Now both SGP and the mount will agree as to where the mount is pointing. You might also want to calibrate PHD2 at this point.

You can then open the Target Setting dialog box for M104 and click “Slew Now” and once the scope has stopped click “Center Now.” You ready to image M104.

You pretty much want to have all your target settings done in advance just so they are available when you need them.

Charlie

I think that all mounts will behave differently based on the “Sync Behavior” setting in the Telescope control panel.

As usual they will likely want logs so I would provide a link to one if you can. But even without a log - if you can check what that setting is that will help.

I saw runaway behavior when I used Sync Behavior = Scope Offset. See my recent posting on scope centering with cge-pro.

Frank

Thanks, Charlie. I don’t have a handbox so I’m just using the AP driver that pops up when I connect to it in SGP. I know the mount isn’t synced correctly, but that’s what I’ve been trying to do for more than a week. I’ll try your suggestions - a different part of the sky - and see what happens.

Where do I find the solve and sync button? Under the plate solve tab?

Thanks!

MJ

I am having this problem now August 2017 on one target NGC7822.
Nothing I have tried solves the problem on this target.

See my post “Mosaic event Ioptron mount slewing out of control”

Were you able to find out what the problem was?
Unless I can sort this I may have to use other software as I often control remotely.
Any chance of the mount setting off randomly is unacceptable due to possible damage.