Monitoring guide stars

 As with any extended observation, the guide star should be monitored, especially in bad seeing or cirrus conditions. If the telescope loses its lock on the guide star and begins to drift, use the second terminal to run the stopall command, which will pause the integration, and then disable the guider. Do not touch any button on the guider, except the toggle switch to disable the telescope guiding. Especially do not touch the buttons that control the crosshair cursor position or the position of the guider camera. The basic idea is that it is the telescope that has drifted off, not the guider. Therefore, we must correct the position of the telescope, not the position of the guider.

When the guide star has stabilized again, use the telescope paddle to drive the guide star back into the crosshair. After the star is repositioned, turn the guider back on. When guiding appears to be stable again, type rego to restart the integration. Depending on the extent of time over which guiding was disabled, you may have to re-take the frame entirely. Use the stopall and ready commands to remove the partially completed exposure, and allow the cube to continue. The aborted frame may need to be retaken manually at the end of the sequence.