The behavior of the deck-axis while tracking a source.

Input Format:

An option from:

• track - Maintain the deck angle equal to the parallactic angle of the source + the current deck-angle tracking offset.
• zero - Set the deck angle equal to the current deck-angle tracking offset.

Track mode:

By default the position of the deck drive is continually adjusted while tracking a source such that the source appears to stay at a fixed rotation angle about the center of the field. The actual orientation angle is set by the deck-angle tracking offset that was last set with the offset command. This is refered to above as "track" mode.

Zero mode:

An alternative tracking mode involves holding the deck at a fixed angle. In this mode, as one tracks a source across the sky, it will appear to rotate about the center of the field. This mode is primarily designed for use during pointing calibration. The fixed deck angle is set by the current deck-angle tracking offset, as set with the offset command. This is refered to as "zero" because it involves tracking zero deck angle plus an optional tracking offset.