AO (3 Hz) ................................... NON-AO
(ST-7 Image segments magnified 2X using IDL)
The above two image segments were extracted from one AO image using 3 Hz corrections (on the left) and a NON-AO image taken just minutes later (on the right). Both images were made on a night when the seeing was only fair ( ~ 2 arc seconds).
In order to get a real comparison of the effects of AO vs NON-AO imaging it is necessary to completely disengage the AO-7 device. Traditional tracking using the drives on the mount creats slow responses as well as backlash effects. Even at SLOW correction speeds the AO-7 provides instantaneous movements and no backlash and contributes to a substantial image improvement. While the best results are obtained under better seeing conditions, some gains of ~10-20% can be realized even on nights of fair to poor seeing.
The above images were from a sequence of images searching for a faint fast moving asteroid. In addition to the better star images, there is also an improvement in the limiting magnitude as ween in these comparison images. In the NON-AO image, the 19'th mag asteroid was not to be found.
In the midst of doing a bunch of asteroid shots this summer I managed to totally demolish a bearing in my clock drive on my GM-200. The damage to the bearing made the drive totally useless without the AO-7 device as the damage created large erratic errors in the drive's motions. However, with the AO-7 engaged even at low tracking rates, the drive was fully useful and my imaging work was not interrupted while the drive was being repaired.