A coordinate system calibration jig that includes radiopaque elements arranged in a fixed predetermined pattern and configured, in response to the radiopaque elements generating a fluoroscopic image, to define a position of the jig in a fluoroscopic coordinate system of reference. The jig further including one or more connectors configured to receive magnetic sensors in respective predetermined fixed locations and orientations with respect to the jig, so that signals from the magnetic sensors in response to a magnetic field traversing the sensors characterize the position of the jig in a magnetic coordinate system of reference defined by the magnetic field.