$LastChangedDate: 27-Juil-2011 $

# CL_gm_eclipseCir

Analytical eclipse calculation for circular orbits

## Calling Sequence

       [result] = CL_gm_eclipseCir(sma,inc,raan,alpha_sun,delta_sun [,er,mu])

## Description

- Computes various results that characterize the portion of the orbit path where the satellite is in the shadow of the planet.

- Notes:

  This function is actually an interface to CL_gm_eclipse, which is called with zero values for eccentricity and argument of periapsis).

  See CL_gm_eclipse for more details.

## Parameters

sma:

  Semi major axis [m] (1xN)

inc:

  Inclination [rad] (1xN)

raan:

  Right ascension of ascending node [rad] (1xN)

alpha_sun:

  Sun right ascension [rad] (1xN)

delta_sun:

  Sun declination [rad] (1xN)

er:

  (optional) Equatorial radius [m] (default is %CL_eqRad)

mu:

  (optional) Gravitational constant [m^3/s^2] (default value is %CL_mu)

result:

  (structure) Various quantities that define the eclipse [rad,sec] (each field is 1xN)

## Authors

- CNES - DCT/SB

## See also

- CL_gm_eclipse

- CL_gm_betaEclipse

## Examples

    cjd = CL_dat_cal2cjd(2009,03,21,6,0,0);
    [r_sun,rs] = CL_mod_moonSunG50(cjd,'s');
    sun_sph = CL_co_car2sph(r_sun);
    alpha_sun = sun_sph(1,:);
    delta_sun = sun_sph(2,:);
    raan = 0;
    sma = 1000.e3+%CL_eqRad;
    inc = CL_deg2rad(98);
    [result] = CL_gm_eclipseCir(sma,inc,raan,alpha_sun,delta_sun);
    result.start
    result.end
    result.sun_orb
    result.angle
    result.duration