GRIP Blob Positions

Hello,

I am trying to get into vision tracking running on the driver station laptop using GRIP. Currently I am using blobs and then writing them to a networktable with the position x,y and the size.

What I am wondering is where are the x and y values located for the blob. Are they at the center of the circle, top left corner, or what?

Thanks

BoundingRect is top left corner.