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Guiding Comments



Setting your maximum allowable error depends on many factors; seeing conditions, wind speed, the accuracy of your mount, the image scale of your imaging setup, etc. Finding the right balance of your systems capabilities and when you should issue a correction takes some experimentation. I have provided these illustrations to help with this process.




In this common example, we see a situation where the seeing and mount accuracy of the imaging system are ~1.00 arc-seconds. The minimum movement is set very low at 0.30" arc-seconds. The guide star centroid is staying well within the systems capabilities, yet the autoguider relays are making unnecessary corrections leading to mount oscillations, over-corrections, unpredictable movements because of backlash, etc. In this example, the stellar profiles of the stars in the image are going to be distorted unnaturally because of poor autoguiding settings.

 




By increasing our maximum allowable peak to peak error to 1 arc-second we only make corrections when the guide star centroid falls out of our systems capabilities i.e. when a correction is truly needed. As you can see we have reduced unnecessary guider corrections which will result in better stellar profiles and rounder stars.

 




Here we have an example of the maximum allowable error being set to high. This could be the same imaging system on a night of excellent seeing or a different imaging system with a more accurate mount. As you can see, guide star centroids outside of our capabilities are not being corrected.

 




By reducing the maximum allowable error to 0.60" arc-seconds, we are now correcting for the movements that fall out of our systems capabilities.