Selection prerequisites: Any number of objects including at least one point
The keyboard shortcut for Mark Center is Shift+Ctrl+F (Windows) or Shift-F (Mac).
To mark a center:
•Select a point and choose Transform | Mark Center, or
•Double-click a point with the Selection Arrow tool.
The marked point will flash briefly to indicate it’s been marked as the center for future rotations and dilations. Once marked, this center point will be used for all future rotations and dilations until you mark a different center point.