Acronyms
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GAST
Greenwich Apparent Sidereal Time
GCAS
Ground Control Approach System
GCRS
Geocentric Celestial Reference System
GDL
Gas Dynamic Laboratory
GE
General Electronic Company
GEO
Geostationary Orbit
GINS
Gimbaled Inertial Navigation System
GIOVE
Galileo In-Orbit Validation Element
GIRD
Group for the Study of Reactive Motion (the acronym in Russian)
GLONASS
Global Navigation Satellite System
GLST
GLONASS Time
GMST
Greenwich Mean Sidereal Time
GMT
Greenwich Mean Time
GNSS
Global Navigation Satellite System
GPS
Global Positioning System
GPST
GPS Time
GRGS
Grope de Recherche en Géodésie Spatiale (French)
GSFC
Goddard Space Flight Center
GST
Galileo Navigation Satellite System Time
HEAO
High-Energy Astrophysics Observatory
HEXTE
High-Energy X-ray Timing Experiment
HMXB
High-Mass X-ray Binary
HST
Hubble Space Telescope
HTPC
High Time-resolution Photon Counter
HXMT
Hard X-ray Modulation Telescope
IAA
International Academy of Astronautics
IAC
International Astronautical Congress
IAF
International Astronautical Federation
IALA
International Association of Lighthouse Authorities
IAU
International Astronomical Union
IBM
International Business Machines Corporation
ICAO
International Civil Aviation Organization
ICBM
Inter-Continental Ballistic Missiles
ICG
International Committee on Global navigation satellite system
ICRF
International Celestial Reference Frame
ICRS
International Celestial Reference System
IERS
International Earth Rotation and Reference Systems Service
IGEB
Interagency GPS Executive Board
IGN
Institut Géographique National (French)
IGSO
Inclination Geo-Synchronization Orbit
ILS
Instrument Landing System
IMU
Inertial Measurement Units
IND
Interplanetary Network Directorate
INS
Inertial Navigation System
INTEGRAL International Gamma-Ray Astrophysics Laboratory