Observations

Passive: Natural Signals Photographs

Semi-Passive: Artificial Signals GPS receiver

Active: Signals Controlled by Observers Radar Echo, Laser Ranging

Passive Observations

Astrographs: 2-dim. Angles Photographic Plates, CCD Arrays, VTR

Transit, Meridian Circle: 1-dim. Angle Interferometry: Precise 1-dim. Angle

VLBI, Optical/IR Int., X-ray Ground-based vs Orbital platform

Passive Observations (Cont.) Detectors: Arrival Time, Energy

Photo-Multiplier Tube, Photo-Diode, CCD, Chamber

Clocks: Event Time Eclipse, Occultation, Pulse, Light

Curve, Rise/Decay Pattern Doppler: Radial Velocity

Spectrograph, Emission/Absorption Lines

Semi-Passive Observations Doppler

Up/Down Link to Satellites/Space Vehicles

Integrated Doppler NNSS, DORIS/PRARE

Semi-Passive VLBI ALSEP, RISE

Time Difference GPS, GLONASS

Active Observations

Radar Bombing Mercury, Venus, Mars, Asteroids

Range and Range Rate (R&RR) Artificial Satellites, Space Vehicles

Radio Transponder Laser Ranging

Satellite, Moon