Name

CL_gm_beta2raan — Beta to right ascension of ascending node angle

Calling Sequence

   [raan1,raan2] = CL_gm_beta2raan(betaa,inc,alpha_sun,delta_sun)
   
   

Description

  • Computes right ascension of ascending nodes (raan1 and raan2) from beta (angle between the satellite's orbital plane and the Sun), alpha_sun (sun's right ascension), delta_sun (sun's declination) and inc (orbit's inclination).

    Notes : - if beta is positive then the sun is in the same direction as the kinetic momentum

    : - There are 2 solutions : raan2 = pi - raan1 + 2*alpha_sun

    : - raan1 is in the interval [ alpha_sun - pi/2 ; alpha_sun + pi/2] modulo 2*pi

    : - raan2 is in the interval [ alpha_sun + pi/2 ; alpha_sun + 3*pi/2] modulo 2*pi

  • Last update : 19/5/2008

Parameters

betaa:

beta angle [rad] (1xN)

inc:

orbit's inclination [rad] (1xN)

alpha_sun:

sun's right ascension[rad] (1xN)

delta_sun:

sun's declination [rad] (1xN)

raan1:

right ascension of the orbit's ascending node (first solution) [rad] (1xN)

raan2:

right ascension of the orbit's ascending node (second solution) [rad] (1xN)

See also

CL_op_locTime, CL_gm_raan2beta, CL_mod_moonSunG50

Authors

CNES - DCT/SB

Examples

// Get alpha_sun and delta_sun
cjd = 20050;
[r_sun,rs] = CL_mod_moonSunG50(cjd,'s');
r_sph = CL_co_car2sph(r_sun);
alpha_sun = r_sph(1);
delta_sun = r_sph(2);
betaa = %pi/4;
inc = CL_deg2rad(98.7);
[raan1,raan2] = CL_gm_beta2raan(betaa,inc,alpha_sun,delta_sun)