ESA Data Ontology
type: ConceptScheme
type: Ontology

GPS
type: Concept

GAP
type: Concept
definition: GAP (GPS Attitude and Positioning Experiment) instrument objective is to measure S/C velocity and attitude as well as TEC (Total Electron Content) of the ionosphere. The relative phase delay of signals in both the L1 and L2 bands from a GPS satellite occulted by the limb ionosphere provide large-scale (1000's of km) information on how the total electron content responds to magnetospheric perturbations. GAP consists of two components: - GAP-A: Three single-frequency (L1) GPS receivers and four patch antennas. This package is being used to provide an accurate absolute time reference, spacecraft 3-D attitude, and post-processed spacecraft position and velocity. - GAP-O: The objective is to provide ionospheric tomography observations.
in scheme: ESA Data Ontology

CASSIOPE
type: Concept
notation: CA

GAP
type: Concept