Re: leveling the RAPAS on Mach2
weihaowang
Hi,
Perhaps as you said, it doesn't matter that much. But I really want to make things right, and I hope someone can answer me about the squareness between the top surface of the RA motor box and the polar scope. If this is the case, then an inclinometer in a cell phone can easily solve the problem.
And as Hilmo said, it is exactly the wrong clock angle that concerns me. Polaris is roughly 0.8 degree from the pole. An error of 2 degrees (or 8 minutes) in the clock angle (a 2 degree tilt of the tripod) translates to 1.7 arcmin of polar alignment error. For guided exposure of less than 10 minutes with a guide-star inside the FoV of a few degrees, the 1.7 arcmin of polar alignment is probably OK and will not introduce observable field rotation within the single exposures. However, the polar alignment error introduced by the tripod tilt is just one of the error budgets. There can be other polar errors, and all the errors can add up. So I want to do my best to control the error associated with the tripod tilt.
Cheers,
Wei-Hao
--
Perhaps as you said, it doesn't matter that much. But I really want to make things right, and I hope someone can answer me about the squareness between the top surface of the RA motor box and the polar scope. If this is the case, then an inclinometer in a cell phone can easily solve the problem.
And as Hilmo said, it is exactly the wrong clock angle that concerns me. Polaris is roughly 0.8 degree from the pole. An error of 2 degrees (or 8 minutes) in the clock angle (a 2 degree tilt of the tripod) translates to 1.7 arcmin of polar alignment error. For guided exposure of less than 10 minutes with a guide-star inside the FoV of a few degrees, the 1.7 arcmin of polar alignment is probably OK and will not introduce observable field rotation within the single exposures. However, the polar alignment error introduced by the tripod tilt is just one of the error budgets. There can be other polar errors, and all the errors can add up. So I want to do my best to control the error associated with the tripod tilt.
Cheers,
Wei-Hao
--
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