An important aspect of telescope control is to make sure that the telescope is tracking the sky at the right rate. Major motors ensure that this is done approximately, by matching the telescope’s position to the Earth’s rotation. But fine-tuning is usually required, and the practice of making these fine-tuned changes is known as “guiding”.
Recently, the SDSS Engineering Crew at Las Campanas Observatory in Chile made a tremendous step forward by figuring out how to guide with the du Pont telescope. APOGEE-South will rely on guiding in order to stay on target while it is making observations. Here is a picture of the guiding camera on the telescope, along with a number of people who worked to make this happen:
John Parejko also created a 30-second movie showing what guiding data look like. The bright “dots” in the video are stars that are being kept in their place by means of the guiding operations.