these 'mascons' comes from small changes noted in the motion of Lunar Orbiter 5, when very precise radio Doppler tracking
was continued for 80 consecutive circuits of the moon....
DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite:) Doppler tracking
antenna receives ground signals for precise orbit determination, satellite tracking, and ionospheric correction data for the altimeter
This chapter includes angle, range and Doppler tracking
, and concludes with Kalman filtering.