87 lines
1.9 KiB
C
87 lines
1.9 KiB
C
#include "astro.h"
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void
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star(void)
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{
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double xm, ym, zm, dxm, dym, dzm;
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double xx, yx, zx, yy, zy, zz, tau;
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double capt0, capt1, capt12, capt13, sl, sb, cl;
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/*
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* remove E-terms of aberration
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* except when finding catalog mean places
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*/
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alpha += (.341/(3600.*15.))*sin((alpha+11.26)*15.*radian)
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/cos(delta*radian);
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delta += (.341/3600.)*cos((alpha+11.26)*15.*radian)
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*sin(delta*radian) - (.029/3600.)*cos(delta*radian);
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/*
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* correct for proper motion
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*/
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tau = (eday - epoch)/365.24220;
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alpha += tau*da/3600.;
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delta += tau*dd/3600.;
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alpha *= 15.*radian;
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delta *= radian;
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/*
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* convert to rectangular coordinates merely for convenience
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*/
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xm = cos(delta)*cos(alpha);
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ym = cos(delta)*sin(alpha);
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zm = sin(delta);
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/*
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* convert mean places at epoch of startable to current
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* epoch (i.e. compute relevant precession)
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*/
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capt0 = (epoch - 18262.427)/36524.220e0;
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capt1 = (eday - epoch)/36524.220;
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capt12 = capt1*capt1;
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capt13 = capt12*capt1;
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xx = - (.00029696+26.e-8*capt0)*capt12
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- 13.e-8*capt13;
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yx = -(.02234941+1355.e-8*capt0)*capt1
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- 676.e-8*capt12 + 221.e-8*capt13;
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zx = -(.00971690-414.e-8*capt0)*capt1
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+ 207.e-8*capt12 + 96.e-8*capt13;
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yy = - (.00024975+30.e-8*capt0)*capt12
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- 15.e-8*capt13;
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zy = -(.00010858+2.e-8*capt0)*capt12;
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zz = - (.00004721-4.e-8*capt0)*capt12;
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dxm = xx*xm + yx*ym + zx*zm;
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dym = - yx*xm + yy*ym + zy*zm;
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dzm = - zx*xm + zy*ym + zz*zm;
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xm = xm + dxm;
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ym = ym + dym;
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zm = zm + dzm;
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/*
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* convert to mean ecliptic system of date
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*/
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alpha = atan2(ym, xm);
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delta = atan2(zm, sqrt(xm*xm+ym*ym));
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cl = cos(delta)*cos(alpha);
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sl = cos(delta)*sin(alpha)*cos(obliq) + sin(delta)*sin(obliq);
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sb = -cos(delta)*sin(alpha)*sin(obliq) + sin(delta)*cos(obliq);
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lambda = atan2(sl, cl);
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beta = atan2(sb, sqrt(cl*cl+sl*sl));
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rad = 1.e9;
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if(px != 0)
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rad = 20600/px;
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motion = 0;
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semi = 0;
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helio();
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geo();
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}
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