|
Matt,
Jim Riffle once told me thousands of
years ago that guiding on a star that was not in the central area of the imaging
FOV would result in trailed stars no matter how well the scope was polar
aligned. I didn't believe him... it didn't make sense... but he's right. I have
taken images with a scope that was dead nuts polar aligned, but with a guide
star at the edge of the FOV and sure enough... trailed stars.
Does anyone have an explanation for this? I guess
it might have to do with angular velocities... in a given time a set part of the
sky will move a greater distance than another part? Like to hear what the more
mathematically gifted than me can make of this.
Tony
|