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CelestLab >> Geometry and events > CL_gm_stationElevation

CL_gm_stationElevation

Elevation of any object as seen from ground stations.

Calling Sequence

[elev] = CL_gm_stationElevation(pos_ter,stations,[er,[obla]])

Description

Parameters

pos_ter:

positions in the rotating frame, in cartesian coordinates [X;Y;Z] [m] (3xM)

stations:

stations positions in the same rotating frame, in elliptical (geodetic) coordinates [long,lat,alt] [rad,m] (3xN)

er :

(optional) planet equatorial radius (default is %CL_eqRad) [m] (1x1)

obla :

(optional) planet oblateness (default is %CL_obla) (1x1)

elev:

elevations from each stations and each object position. elev(row=i,column=j) is the elevation of object j from station i. [rad] (NxM)

Authors

See also

Examples

//secular J2 propagation
cjd0 = 21915;
pas = 10./86400.0;
cjd = cjd0 : pas : cjd0+1;
kep0 = [7070.e3 ; 0.001 ; CL_deg2rad([98;90;10;15])];
kep = CL_ex_secularJ2(cjd0, kep0, cjd);

//conversion to terrestrial frame
[pos_car,vel_car] = CL_oe_kep2car(kep);
pos_ter = CL_fr_G502ter(cjd,pos_car);

//stations definition
sta1 = [CL_deg2rad(2);CL_deg2rad(70);200]; // high latitude
sta2 = [CL_deg2rad(20);CL_deg2rad(0);400]; // equator
stations = [sta1,sta2];

//elevations computation
[elev] = CL_gm_stationElevation(pos_ter,stations);

// elevation in function of time
scf();
plot2d((cjd-cjd0)*24,CL_rad2deg(elev(1,:)),2) //station 1
plot2d((cjd-cjd0)*24,CL_rad2deg(elev(2,:)),3) //station 2

// visibility duration if station's mask is 5 degrees :
ind_1 = find(elev(1,:) > CL_deg2rad(5));  //station 1
ind_2 = find(elev(2,:) > CL_deg2rad(5));  //station 2
dur_1_minutes = pas*length(ind_1)*1440.0
dur_2_minutes = pas*length(ind_2)*1440.0
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