Another really useful feature of the Modify Reference Objects tool is that it makes it easy to define a pivot point, and then to tilt an object or group of objects about this pivot point.

After deleting all the null objects, object 2 is the primary mirror for the first quadrant of the four-telescope array. It is drawn in red below:



Now this object is located at {x,y,z} coordinates of {0, 7.2, 13} and with tilt angles {q_x,q_y,q_z} of {0,0,0} with respect to the global coordinate reference point. However, let us say that the mirror is held in a mount in which the pivot point (the location about which translations and tilts takes place) which is located as follows:

{x,y,z} = {3.5, 10, 16.7}
{q_x,q_y,q_z} = {0, 10, 0}

We now want to make the mirror pivot about that point. To do this is easy. First, click on object 1, and press the {insert} key, so that a null object is inserted and becomes the new object 1. The primary mirror now becomes object 2. Enter the positions and tilts of the null object as above. Double-click on the object type of the null object, go to the Draw tab, and select 'Draw Local Axis'. The 3D layout will now show the pivot point:



Then open the Modify Reference Tools dialog again (on the Non-Sequential Component Editor...Tools menu) and configure it as follows:



Note that the primary mirror position is unchanged, but that the values entered in the Non-Sequential Editor now show the position and tilt of the mirror relative to the pivot point. If the pivot point is shifted or tilted, the mirror will now shift or tilt about this new pivot point.