Hy Murveit replied to the topic 'Drift Plot of Guide Module' in the forum. 3 years ago

What is plotted is the difference between the measured position and the "lock position" or "target" or "guide star position", or whatever you want to call it. This difference tuple (also called "drift") is what's used when calculating the correction pulses to be sent to the RA and DEC motors--units are arc-seconds, and axes point in the RA and DEC directions (as determined by calibration).

This lock position is set at the start of guiding, and changes when dithering, or when the guiding restarts due to a slew, meridian-flip, or lost guide-star. So, the ideal value is 0,0 meaning, the measured position is exactly where we want it to be.

The same values are plotted on the "Drift Plot" and "Drift Graph" of the Guider tab, as well as the RA and DEC graphs in the Analyze tab.

BTW, calibration is something else--it does not determine the lock position. Often, though, the lock position is set right after calibration.

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