Focus the receiver according to the elevation and ambient temperature.

Arguments:

(none)

Example:

The following example tells the control system to attempt to move the receiver to the optimal focus position for the current pointing elevation of the telescope and the ambient temperature. It then waits for the focusing operation to complete.

  focus
  until $acquired(focus)

Context:

The optimal focus of the telescope changes with elevation and the ambient temperature. How it changes should be specified by installing focus curves, using the focus_curve command, and, for the highest frequency receivers, the focus_tcurve command. The focus command identifies the appropriate focus curve for the current temperature, and linearly interpolates this curve for the optimal focus position of the current telescope elevation. It then attempts to set this focus position, as described for the set_focus command.

A schedule can await the completion of a focusing operation using the until statement with the acquired() function, as follows:

  until $acquired(focus)

Thereafter, the focus_acquired() function can be used to determine whether the focus position was successfully acquired, or whether the operation timed out.

  if($focus_acquired()) {
    print "The focus position was successfully acquired."
  } else {
    print "The focus position was not successfully acquired."
  }