This list is made up of the "defining constants" (natural or auxiliary), which are constants fixed by convention together with the list of Current Best Estimates, all of which are determined by the NSFA Working Group. The NSFA WG will update these constants as and when research produces better values.
Click on one of the following constants to jump to the section with the current best estimate and all the relevant details and references.
CONSTANTS FIXED BY CONVENTION  
DEFINING  Speed of Light  L_{G}  L_{B}  TDBTCB at T_{0} 
Astronomical Unit  Earth Rotation Angle  Rate of ERA  
CURRENT BEST ESTIMATES  
MEASURABLE  Gravitation Const.  
OTHER  L_{C}  
BODY CONSTANTS  Earth Radius  Dynamical F.F. J_{2}  Variation in J_{2}  
Geocentric Grav.  Potential of Geoid  Earth Velocity  
Solar Mass  Mass Moon / Earth  
Mass Mercury  Mass Venus  Mass Mars  
Mass Jupiter  Mass Saturn  Mass Uranus  Mass Neptune  
Mass Pluto  Mass Eris  
Mass Ceres  Mass Pallas  Mass Vesta  
INITIAL VALUES  Obliquity of Ecliptic 
Speed of Light  c = 2.997 924 58 x 10^{8} m s^{−1}  c 
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1−d(TT)/d(TCG)  L_{G} = 6.969 290 134 x 10^{−10}  L_{G} 
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1−d(TDB)/d(TCB)  L_{B} = 1.550 519 768 x 10^{−8}  L_{B} 
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TDB − TCB at T_{0}  TDB_{0} = −6.55 x 10^{−5} s  TDB_{0} 
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Astronomical unit  au = 1.495 978 707 00 x 10^{11} m  au 
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Earth Rotation Angle at J2000.0 Rate of advance of Earth Rotation Angle 
θ_{0} = 0.779 057 273 2640 revolutions dθ/dUT1 = 1.002 737 811 911 354 48 revolutions UT1day^{−1} 
θ_{0} dθ/dUT1 
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Constant of gravitation  G = 6.674 28 x 10^{−11} m^{3}kg^{−1}s^{−2}  G 
Uncertainty:  6.7 x 10^{−15} m^{3}kg^{−1}s^{−2}  
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Average value of 1−d(TCG)/d(TCB) 
L_{C} = 1.480 826 867 41 x 10^{−8}  L_{C} 
Uncertainty:  2 x 10^{−17}  
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Solar mass parameter  GM_{S} = 1.327 124 420 99 x 10^{20} m^{3}s^{−2} [TCBcompatible] GM_{S} = 1.327 124 400 41 x 10^{20} m^{3}s^{−2} [TDBcompatible] 
GM_{S} 
Uncertainty:  1.0 x 10^{10} m^{3}s^{−2} [TCBcompatible] 1.0 x 10^{10} m^{3}s^{−2} [TDBcompatible]  
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Equatorial radius of the Earth  a_{E} = 6.378 1366 x 10^{6} m [TTcompatible]  a_{E} 
Uncertainty:  1 x 10^{−1} m [TTcompatible]  
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Dynamical form factor  J_{2} = 1.082 6359 x 10^{−3}  J_{2} 
Uncertainty:  1 x 10^{−10}  
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Time rate of change in J_{2}  dJ_{2}/dt = −3.0 x 10^{−9} cy^{−1}  dJ_{2}/dt 
Uncertainty:  6 x 10^{−10} cy^{−1}  
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Geocentric gravitational constant  GM_{E} = 3.986 004 418 x 10^{14} m^{3}s^{−2} [TCBcompatible] GM_{E} = 3.986 004 415 x 10^{14} m^{3}s^{−2} [TTcompatible] GM_{E} = 3.986 004 356 x 10^{14} m^{3}s^{−2} [TDBcompatible] 
GM_{E} 
Uncertainty:  8 x 10^{5} m^{3}s^{−2} [TCBcompatible] 8 x 10^{5} m^{3}s^{−2} [TTcompatible] 8 x 10^{5} m^{3}s^{−2} [TDBcompatible]  
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Potential of the geoid  W_{0} = 6.263 685 60 x 10^{7} m^{2}s^{−2}  W_{0} 
Uncertainty:  5 x 10^{−1} m^{2}s^{−2}  
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Nominal mean angular velocity of the Earth  ω = 7.292 115 x 10^{−5} rad s^{−1} [TTcompatible]  ω 
Uncertainty:  (see Notes)  
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Ratio mass of the Moon to the Earth  M_{M}/M_{E} = 1.230 003 71 x 10^{−2}  M_{M}/M_{E} 
Uncertainty:  4 x 10^{−10}  
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Ratio of the mass of the Sun to Mercury  M_{S}/M_{Me} = 6.0236 x 10^{6}  M_{S}/M_{Me} 
Uncertainty:  3 x 10^{2}  
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Ratio of the mass of the Sun to Venus  M_{S}/M_{Ve} = 4.085 237 19 x 10^{5}  M_{S}/M_{Ve} 
Uncertainty:  8 x 10^{−3}  
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Ratio of the mass of the Sun to Mars  M_{S}/M_{Ma} = 3.098 703 59 x 10^{6}  M_{S}/M_{Ma} 
Uncertainty:  2 x 10^{−2}  
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Ratio of the mass of the Sun to Jupiter  M_{S}/M_{J} = 1.047 348 644 x 10^{3}  M_{S}/M_{J} 
Uncertainty:  1.7 x 10^{−5}  
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Ratio of the mass of the Sun to Saturn  M_{S}/M_{Sa} = 3.497 9018 x 10^{3}  M_{S}/M_{Sa} 
Uncertainty:  1 x 10^{−4}  
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Ratio of the mass of the Sun to Uranus  M_{S}/M_{U} = 2.290 298 x 10^{4}  M_{S}/M_{U} 
Uncertainty:  3 x 10^{−2}  
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Ratio of the mass of the Sun to Neptune  M_{S}/M_{N} = 1.941 226 x 10^{4}  M_{S}/M_{N} 
Uncertainty:  3 x 10^{−2}  
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Ratio of the mass of the Sun to (134340) Pluto  M_{S}/M_{P} = 1.365 66 x 10^{8}  M_{S}/M_{P} 
Uncertainty:  2.8 x 10^{4}  
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Ratio of the mass of the Sun to (136199) Eris  M_{S}/M_{Eris} = 1.191 x 10^{8}  M_{S}/M_{Eris} 
Uncertainty:  1.4 x 10^{6}  
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Ratio of the mass of (1) Ceres to the Sun  M_{Ceres}/M_{S} = 4.72 x 10^{−10}  M_{Ceres}/M_{S} 
Uncertainty:  3 x 10^{−12}  
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Ratio of the mass of (2) Pallas to the Sun  M_{Pallas}/M_{S} = 1.03 x 10^{−10}  M_{Pallas}/M_{S} 
Uncertainty:  3 x 10^{−12}  
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Ratio of the mass of (4) Vesta to the Sun  M_{Vesta}/M_{S} = 1.35 x 10^{−10}  M_{Vesta}/M_{S} 
Uncertainty:  3 x 10^{−12}  
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Obliquity of the ecliptic at J2000.0  ε_{J2000} = 8.438 1406 x 10^{4} "  ε_{J2000} 
Uncertainty:  1 x 10^{−3} "  
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