$LastChangedDate: 27-Juil-2011 $

# CL_gm_raan2beta

Right ascension of ascending node to beta angle

## Calling Sequence

       [betaa] = CL_gm_raan2beta(inc,raan,alpha_sun,delta_sun)

## Description

- Computes the beta angle (betaa), which is the angle between the orbit plane and the Sun direction.

  The beta angle is a function of the orbit's right ascension of ascending node (raan) and inclination (inc) and the Sun's right ascension (alpha_sun) and declination (delta_sun).

- Note:

  Beta is a signed quantity. It is positive when the Sun direction is less than 90 degrees from the orbit's angular momentum vector.

## Parameters

inc:

  Orbit inclination [rad] (1xN)

raan:

  Orbit right ascension of ascending node [rad] (1xN)

alpha_sun:

  Sun right ascension [rad] (1xN)

delta_sun:

  Sun declination [rad] (1xN)

betaa:

  Beta angle [rad] (1xN)

## See also

- CL_gm_beta2raan

## 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);
    raan = %pi/4;
    inc = CL_deg2rad(98.7);
    betaa = CL_gm_raan2beta(inc,raan,alpha_sun,delta_sun)