Compare gravity models
Compare the gravity models for both normalized and unnormalized coefficients.
Reference: Gottlieb, R. G., "Fast Gravity, Gravity Partials, Normalized Gravity, Gravity Graident Torque and Magnetic Field: Derivation, Code and Data, NASA CR 188243, February, 1993.
See also UnnormalizeGravity, AGravityC
Contents
%-------------------------------------------------------------------------- % Copyright (c) 2016 Princeton Satellite Systems, Inc. % All rights reserved. %-------------------------------------------------------------------------- % Since 2016.1 %--------------------------------------------------------------------------
GEM-10 - normalized coefficients
m 1 2 3 4
gEM10.c = [ 0.00104 2.43404 0.0 0.0 % 2 2.02855 0.89272 0.70028 0.0 % 3 -0.53521 0.35208 0.98850 -0.19531 ]; % 4 gEM10.s = [-0.00243 -1.39907 0.0 0.0 % 2 0.25197 -0.62346 1.41250 0.0 % 3 -0.46926 0.66404 -0.20179 0.29883 ]; % 4 gEM10.c = [zeros(1,4);gEM10.c]*1e-6; gEM10.s = [zeros(1,4);gEM10.s]*1e-6; gEM10.j = [0 -484.16544 0.95838 0.54112]*1e-6; gEM10.mu = 398600.47e9; gEM10.a = 6378139.0; gEM10.isNormalized = true; % Reference location r = [5489150;802222;3140916]; % m % Degree and order of model nZ = 4; nM = 4; % Reference acceleration, m/s2 aRef = [-8.44269212018857;-1.23393633785485;-4.84659352346614]; % m/s2 % Unnormalized coefficients gEM10U = UnnormalizeGravity( gEM10 ); DispWithTitle(gEM10U.j,'Unnormalized zonal coefficients:') aTotalC = AGravityC( r, nZ, nM, gEM10U ); % Normalized coefficients DispWithTitle(gEM10.j,'Normalized zonal coefficients:') aTotalN = AGravityC( r, nZ, nM, gEM10 ); fprintf(1,'Reference data: [%24.16f %24.16f %24.16f]\n',aRef); fprintf(1,'AGravityC: [%24.16f %24.16f %24.16f]\n',aTotalC); fprintf(1,'Delta: [%24.16f %24.16f %24.16f]\n',aTotalC-aRef); fprintf(1,'AGravity, Normalized: [%24.16f %24.16f %24.16f]\n',aTotalN); fprintf(1,'Delta: [%24.16f %24.16f %24.16f]\n',aTotalN-aRef); %--------------------------------------
Unnormalized zonal coefficients:
0 -0.0010826 2.5356e-06 1.6234e-06
Normalized zonal coefficients:
0 -0.00048417 9.5838e-07 5.4112e-07
Reference data: [ -8.4426921201885694 -1.2339363378548500 -4.8465935234661401]
AGravityC: [ -8.4426921201885712 -1.2339363378548491 -4.8465935234661419]
Delta: [ -0.0000000000000018 0.0000000000000009 -0.0000000000000018]
AGravity, Normalized: [ -8.4426921201885712 -1.2339363378548491 -4.8465935234661419]
Delta: [ -0.0000000000000018 0.0000000000000009 -0.0000000000000018]