title: Astronomical applications of differential interferometry.
abstract: Intercomparison of radio signals received simultaneously at several sites from several sources with small mutual angular separation provides a powerful astrometric tool. Applications include tracking the Lunar Rover relative to the Lunar Module, determining the moon's libration, measuring winds in Venus's lower atmosphere, mapping Mars radiometrically, and locating the planetary system in an inertial frame.
authors.forename: C C
authors.initials: CC
authors.lastname: Counselman
authors.forename: H F
authors.initials: HF
authors.lastname: Hinteregger
authors.forename: I I
authors.initials: II
authors.lastname: Shapiro