CL_gm_eclipseCir — Analytic eclipse calculation for circular orbits
[eclipseS,eclipseE,sun_orb,duration] = CL_gm_eclipseCir(cjd,sma,inc,raan[,er[,mu[,j2]]])
Orbit's node is defined by its right ascension (raan).
The eclipse is defined as the satellite crossing a cylinder supported on sun's diameter. Calculation is purely geometric: sun-orbit geometry is constant
eclipseS and eclipseE contain the start and end of eclipse positions : [position on orbit(w+M);right ascension in Gamma50 (Veis);declination in Gamma50 (Veis)]
sun_orb contains sun's right ascension and declination in orbit frame
Orbit frame is defined as follows:
axe X: towards node
axe Z: orbit's kinetic moment vector
axe Y assures orthonormal direct frame
duration contains [total angle of eclipse on orbit;duration] (duration is computed using the meanmotion taking into account J2).
NOTES:
- planet is assumed spherical and it is necessarily the earth
- sun_orb's declination (in orbit frame) is the beta angle (angle between the satellite's orbital plane and the Sun)
CNES julian day (+ut/24, ut in hours) (1xN)
semi major axis [m] (1xN)
inclination [rad] (1xN)
right ascension of ascending node[rad] (1xN)
(optional) equatorial radius [m] (default is %CL_eqRad)
(optional) geocentric gravitational constant [m^3/s^2] (default value is %CL_mu)
(optional) zonal coefficient (second zonal harmonic) (default is %CL_j2)
start of eclipse [position on orbit(w+M);right ascension in Gamma50(Veis);declination in Gamma50(Veis)] [rad] (3xN)
end of eclipse [position on orbit(w+M);right ascension in Gamma50(Veis);declination in Gamma50(Veis)] [rad] (3xN)
sun on orbit frame [right ascension;declination (=beta)] [rad] (2xN)
eclipse duration [angle of position on orbit;duration] [rad;s] (2xN)
//Example 1 cjd=21482; raan=0; sma = 1000000+%CL_eqRad; inc = CL_deg2rad(98); [eS,eE,s_orb,deltaT] = CL_gm_eclipseCir(cjd,sma,inc,raan) // Example 2 cjd = CL_dat_cal2cjd(2009,03,21,6); // march 21 2009, 6am inc = CL_deg2rad(90); sma = 6978.e3; raan = 0; [eS,eE,s_orb,deltaT] = CL_gm_eclipseCir(cjd,sma,inc,raan) // Eclipse position is around 180° of pso...