SabS Now I just need to cut a tree off as its blocking my SCP
Ah, this is the case where you do need to set the declination of the OTA farther away from -90º.
Remember that the polar axis ("RA axis") is still needs to be finally pointed at the SCP (even if you cannot see it). However, by pointing your declination to a position away from the SCP, you can see from a planetarium program (like SkySafari) that you will be describing a constant-declination arc around the pole as you make that 60º RA slew. Use enough declination offset to make an arc above the tree.
(If the OTA is pointed directly at declination -90º, the plate solves at the start and the end will both be centered at the SCP, but one will be rotated relative to the other. I.e., both plates will be centered right on your tree. And that will not let you polar align.)
If it is still not clear how you can avoid the tree, I can draw a couple of diagrams for you.
You also do not need to start at the tip of the tree. You only need to do a plate solve at the first location and multiple plate solves at the post-60º position. In between those two positions, you can be fully obscured and ASIAIR will not care. (Indeed, I start my own Polar Alignment with the declination tilted 60 degrees over, so that after the 60º slew, I have the maximum clearance to get to the bolts of my compact mount.)
You get less accuracy as you plate solve farther from the pole Until it won't solve at all beyond 30º away from the pole. But if you have a low noise CMOS camera, you can probably do as well at 180 second exposures as you can do with 600 second exposures, depending on your Bortle or SQM number. With a 120 to 180 second exposure, your RA axis can be 2 arc minutes from the pole and still be acceptable. Your stacking program should be able to handle the long term field rotation.
30º is a long way from the pole. If you were in Tasmania, the pole is already some 42º above the horizon. So the OTA can actually be pointed 70º from the horizon (that is just 20º from overhead) and you can still get away with it. It is not as favorable at other parts of the continent, though. But I doubt your trees are tall enough to be 30 degrees taller than the SCP. Just make sure the RA axis is close to True South when you start. You will eventually have to nudge it to True south during polar alignment anyway, so might as well also start with it close by. That probably was the cause of the "too far" error that you got.
At least Santa and his sleigh won't be blocking your pole. It is weird though that Santa lives in the north where there is no land mass, while there is a large continent just to the south of you.
Chen
