Send the telescope to the stow position.

Optional qualifier arguments:

/soft

This tells the stow command to perform the stow under software stow control. Without this modifier, stow commands are delegated to special purpose hardware.

Arguments:

(none)

Context:

The stow position is the position where the telescope should be left when it is not observing, because the wind-loading on the telescope is lowest at this position.

The telescope can be stowed under either software servo or hardware synchro control. Hardware mediated stows have the advantage of not relying on the axis encoders, and can thus be executed when an encoder is broken. However this hardware mode relies on the correct functioning of the physical limit switches to terminate stows, and it provides no way to only stow one axis if there is a problem on the other axis.

Hardware mediated stows end at roughly az=180, el=90 degrees, depending on where the terminating physical switches trigger. By default, software mediated stows also end at az=180, el=90 degrees, but this can be changed by calling the stow_pars command.

In the absence of the /soft modifier, the default behavior of the stow command is to perform a hardware mediated stow. However if a malfunction of the azimuth limit-switches or overlap switches has been detected, and the elevation encoder is working, then a software stow of just the elevation axis is performed instead.

The control system can be explicitly told to perform a stow under software servo control by adding the /soft modifier to the stow command. If no axes are currently enabled, then the control system will attempt to enable all axes before initiating this stow, and then stow all of the axes. Otherwise, if one or more axes are already enabled, then the software stow just stows the enabled axes.

If a significant hardware error occurs while stowing, then the telescope is halted. Note that encoder errors are not considered to be significant errors during hardware mediated stows, since the encoders are not used by the stowing hardware. If the error is solely on the azimuth axis, then it may be possible to restart the elevation part of the stow in software servo mode, simply by invoking the stow command again. In such cases it doesn't matter whether the /soft modifier is included or not, since the control system will automatically fallback to the software stow mode in this case. During wind-stows, the re-issuing of stalled stow commands is done automatically, behind the scenes, since it is critical to stow the telescope at such times. At other times, it is up to the observer to either re-issue the stow command, or take other remedial action, after investigating the cause.