Before setting up the AO unit, the camera should be focused and the temperature should be near the Setpoint. Once focused and at a stable temperature the AO unit must be calibrated (see Locate tab). Once you have calibrated your AO unit the settings are stored; you should not need to recalibrate again unless the unit is serviced or equipment such as a filter wheel is inserted between the AO and the camera.
The telescope drive must also be calibrated (see Locate tab) if corrections are enabled for one or more mount axes while autoguiding (see Drive tab). This calibration must be done so that MaxIm DL can correlate the direction the mount moves with the motor relays; if this is not necessary, this function can be turned off. If the orientation of the camera with respect to the telescope motions remains constant the calibration only needs to be done once.
In order to guide an exposure with the AO, a guide star must first be located using the Locate tab. Next, switch to the Track tab, select a Track Time (guider exposure duration), and click Start. If everything works correctly, the guide star should appear and then be pulled into the center of the guide box immediately. The Track Time should be as short as possible to allow for the fastest update rate, but long enough to ensure a clear image of the guide star. To adjust the Track Time, momentarily stop the guider - click the Stop button - dial in the new duration, and click Start again. The Aggressiveness and Max. Move can then be adjusted while autoguiding to tweak the tracking stability.
With a short Track Time, extremely fast guide rates are possible using an AO unit. This provides the optimum guiding and can often have a noticeable effect on the resolution of the resulting images.
Since autoguiding with an AO unit is very CPU intensive, users may find that it is more convenient to stop the AO unit while adjusting the exposure settings in the MaxIm DL control window. Once all the relevant exposure parameters are set, start the AO autoguider and then switch back to the Camera Control window to start the exposure.
MaxIm DL can take sequences of exposures while the autoguider is running. During download the shutter is closed and the guider cannot operate. The SBIG AO Control window will automatically reacquire the guide star after each exposure. If a tricolor sequence is in progress, the software waits for the filter wheel to finish rotating before reacquiring the guide star. However, before starting a tricolor sequence it is a good idea to make sure that the guide star is bright enough when the filter wheel switches to blue.
When taking exposure sequences, at least a five second delay should be inserted between exposures to allow time for the autoguider to settle (use the Delay field in the Expose tab). This is necessary because the guider cannot operate during camera download and the telescope may drift. The software is designed to automatically reacquire the star even if it has drifted out of the track box.
During reacquisition, the SBIG AO Control will take two exposures using the settings on the Locate tab, then start tracking using the settings on the Track tab. This procedure allows it to reacquire the guide star even if it has drifted out of the track box. Sufficient delay time must be allowed for this process to occur before the next exposure starts. Typically a five second delay is sufficient, but this may not be enough if longer tracking exposures are used.