Calibration and validation are important aspects of any remote sensing system. The calibration of the Landsat sensors is supported by preflight, post launch-onboard, and ground reference data.
Calibration Parameter files (CPF) provide radiometric and geometric coefficients needed for processing of raw, uncorrected Landsat image data. Each timeframe specific CPF contains calibration coefficients that have been adjusted to correct for the time varying performance of the sensor.Landsat 8 (L8) OLI/TIRS
Landsat 8 (L8) Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS)
Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+)
Landsat 4-5 Thematic Mapper (TM)
Landsat 1-5 Multi-Spectral Scanner (MSS)
Bias Parameter Files (BPF) supply radiometric correction parameters during Level 1 processing of Landsat 8 data products.
Response Linearization Look Up Tables (RLUT) are optional additional files that accompany Calibration Parameter Files (CPF) and contain a mapping look up table to linearize the output of the OLI detectors. This is done to increase the range of Digital Number (DN) values for preciseness and limit the number of saturated pixels to true saturations, and on the dark end, limit it to missing data. Non-linearity characterization uses a series of variable integration time observations of the solar diffuser and corresponding shutter observations to generate a remapping for every digital number (4096 values per detector) for every detector.
Definitive Ephemeris is used is used to geometrically correct Landsat 4-5 Thematic Mapper and Landsat 7 data. An ephemeris is a set of data that provides the assigned places of a celestial body (including a manmade satellite) for regular intervals. In Landsat 7, definitive ephemeris shows the position and velocity of the satellite in one-minute intervals. Section 11.3.7 of the Landsat 7 Data Users Handbook provides more details on definitive ephemeris.