Hi Gabriel,
I don't know if you have seen one of my earlier posts, where I mentioned that the ASIAIR polar alignment procedure's accuracy does not depend on the starting (or ending) angle of the slew.
You do not need to start with the OTA at the top dead center of the mount (counterweight pointed at ground). All you need are two plate solvable locations that are 60 degrees apart in RA. And there can be obstructions of the view in between those two locations, since ASIAIR does not do any plate solving while it slews.
Many people assume that you need to start with the OTA at the top dead center, and then allow ASIAIR to move the mount the mount to 60 degrees west of the pier. That works -- but it is not a requirement.
In your situation, for example, you can start with the OTA at 60 degrees east relative to the top dead center. After the 60 degree slew, the OTA will be near the position where your counterweight points to the ground. This still gives you two locations for plate solving that are 60 degrees apart. And you will be doing your altitude and azimuth adjustments with the OTA near top dead center (counterweight pointed at ground).
You also need not set the DEC to be set to exactly 90 degrees (which presents computational challenges).
I usually start my mount with the OTA at 30 degrees EAST of the pier with DEC set to 89.5 degrees by using ASIAIR GOTO from my home position -- I have a RainbowAstro RST-135 mount and its home location has the OTA pointed at the west horizon. After rotating, the mount ends up with the OTA at 30 degrees WEST of the pier, with the DEC still at 89.5 degrees.
In fact, you can (in the northern hemisphere) set the DEC up to 30 degrees south from the pole. Beyond 30 degrees from the pole, ASIAIR puts out a warning after the first plate solve that the angle is too large. I.e., you can use DEC as small as 60 degrees, if there is an obstruction near the pole. When I ran the ASIAIR through my mount simulator, however, the polar alignment is not as accurate when you are that far from the pole. Anything between 80 degrees and 89.99 degrees give very consistent results; at 89.5 degrees DEC, my simulator tells me that the results of the solved pole are consistent to better than 10 arc seconds..
Also, I have noticed that when I ran the ASIAIR polar alignment with my mount simulator that depending on the mount, it does not always rotate by 60 degrees. I tested using my simulator's Celestron AVX setting, and ASIAIR seems to rotate by 66 degrees consistently, while my RST-135 is consistently rotated by 60 degrees. Don't worry if it is not 60 degrees, but keep that in mind when you choose your angles to avoid any obstruction of your view in case the mount does not move by exactly 60 degrees.
Good luck,
Chen
