The strike area is as close to center as the fine Windage Adj allows. Note that the target is labeled with its size. In the upper left of the target graph area is a note that the ring dimensions are the radius in inches.

Use a smaller target to get a more detailed view. This is done by clicking the up/down arrow buttons of the Target size control. Once again you can right mouse click on the Target size control to open a menu and select a size as shown next...