Plate solving in the beginning of a sequence


As far as I can tell, SGP starts an imaging sequence with a plate solve before slewing to the first target, even if both “Slew to” and “Center on” are ticked in the target settings. If I’ve understood correctly, ticking both usually first slews to the target without a plate solve and only then starts the iterative centering. So why does the sequence start with a plate solve?

I’m imaging from a roll-off roof observatory, and at the start of a sequence the telescope is usually parked and pointing at a wall, so the sequence wastes precious time trying to solve an image of the wall and risks a false solve result.

Help required with Mosaic centering options


If your target is marked as “Slew To” and “Center On”, then when you click Run Sequence, SGP will issue a slew to the target’s coordinates and then perform a plate solve. Then perform centering by repeating the slew / solve loop. This will continue until the centering limits are achieved or the max tries are exceeded. SGP does not plate solve until your scope is pointing at the target.

However, there could be an issue with attempting to run a sequence with the scope still in a parked position. Some scopes will ignore the initial slew if the scope is parked when that slew is issued. It is good practice to always use the ASCOM driver to unpark the scope first and then run the sequence. Also, I believe the Control Panel / Telescope tab will let you unpark the scope once the scope is connected. I don’t think SGP does an unpark automatically.

If you are actually seeing SGP trying to perform a plate solve while the scope is still pointing at the wall, then you definitely have the parked scope issue.



@chasmiller46 The mount is indeed parked when I start the sequence. However, SGP kindly offers to unpark the scope (and open the slaved roll-off roof) before doing anything else. After the roof is open and the scope is unparked, SGP takes a picture of the wall and tries to plate solve it before slewing anywhere. I don’t see SGP trying to slew the scope before doing the first plate solve. It’s just capturing a plate solve image and trying to sync the scope based on that.


I dug through the logs, and I think the plate solving happens because I have the Manual Rotator connected. The logs say this before any slew commands:

[11.03.17][DEBUG] [Sequence Thread] Sequence requires the rotator, but the rotator has not been synced, plate solving…

I assume the Manual Rotator does not preserve any sync information between sessions? So every time I fire up SGP and start a sequence, the Manual Rotator is unsynced, even if I haven’t touched the camera and I have run Solve & Sync the previous time I had SGP open. I’m running the observatory remotely, so I’m not always there to manually rotate the camera, so it makes sense just to stop using the Manual Rotator.