#include #include #include /***************************************************************************/ /* */ /* precessJulian Julian precession of Equatorial coordinates. */ /* ------------- */ /* */ /* ( see precessJulianWithProperMotion() ) */ /* */ /***************************************************************************/ void precessJulian(double epochin, double rain, double decin, double epochout, double *raout, double *decout) { double rapm, decpm; if(coord_debug) { fprintf(stderr, "DEBUG: precessJulian()\n"); fflush(stderr); } precessJulianWithProperMotion (epochin, rain, decin, epochout, raout, decout, 0., 0., 0., 0., &rapm, &decpm); return ; } /***************************************************************************/ /* */ /* precessJulianWithProperMotion Besselian precession of Equatorial */ /* ----------------------------- coordinates. */ /* */ /* Also allows precession of proper motion values (making use of */ /* parallax and radial velocity if not zero). */ /* */ /* Arguments (all double precision): */ /* */ /* epochin epoch of input position (in year - e.g. 1950.0d0) */ /* rain, decin input position in decimal degrees at epochin */ /* pmain, pmdin proper motion in ra,dec in seconds of time */ /* per Tropical century. */ /* */ /* pin parallax in arc seconds (0.0d0 if none) */ /* vin radial velocity in km/sec (0.0d0 if none) */ /* epochout epoch of output position (in year - e.g. 1992.0d0) */ /* raout, decout position in decimal degrees at epochout */ /* rapm, decpm proper motion in ra,dec in seconds of time */ /* per Tropical century for epochout */ /* */ /***************************************************************************/ void precessJulianWithProperMotion (double epochin, double rain, double decin, double epochout, double *raout, double *decout, double pmain, double pmdin, double pin, double vin, double *rapm, double *decpm) { static double rtod, dtor, delt, f, p[3][3]; static double saveepochin = -1.0; static double saveepochout = -1.0; int i; double zetar, zr, thetar, zeta, z, theta; double tau, t; double r0[3], rdot0[3], r[3], rdot[3], pivelf; double czet, cthet, cz, szet, sthet, sz; double cosa, sina, cosd, sind, rar, decr; double cosao, sinao, cosdo, sindo; double pmas, pmds, rdiv, raoutr, decoutr, rapms, decpms; double duda[3], dudd[3]; if(coord_debug) { fprintf(stderr, "DEBUG: precessJulianWithProperMotion()\n"); fflush(stderr); } /* Requested input is the same as input: No-op */ if(epochin == epochout) { *raout = rain; *decout = decin; *rapm = pmain; *decpm = pmdin; return; } /* First time through for a conversion, set up constants and */ /* the transformation parameters for this specific time change */ if(epochin != saveepochin || epochout != saveepochout) { /* Radians <-> Degrees */ dtor = atan(1.0) / 45.0; rtod = 1.0 / dtor; /* 1 arcsec, in radians */ f = dtor / 3600.; /* TAU, T, DELT in Tropical centuries */ tau = (epochin - 2000.0 ) * 0.01; t = (epochout - epochin) * 0.01; delt = t; /* ZETA, THETA, Z from FK5 Catalogue in seconds of arc */ zeta = (2306.2181 + 1.39656*tau - 0.000139*tau*tau)*t + (0.30188 - 0.000344*tau)*t*t + 0.017998*t*t*t; z = (2306.2181 + 1.39656*tau - 0.000139*tau*tau)*t + (1.09468 + 0.000066*tau)*t*t + 0.018203*t*t*t; theta = (2004.3109 - 0.85330*tau - 0.000217*tau*tau)*t - (0.42665 + 0.000217*tau)*t*t - 0.041833*t*t*t; zetar = ( zeta/3600.0)*dtor; zr = ( z/3600.0)*dtor; thetar = (theta/3600.0)*dtor; czet = cos(zetar); szet = sin(zetar); cz = cos(zr); sz = sin(zr); cthet = cos(thetar); sthet = sin(thetar); /* P matrix */ p[0][0] = czet*cthet*cz - szet*sz; p[1][0] = czet*cthet*sz + szet*cz; p[2][0] = czet*sthet; p[0][1] = -szet*cthet*cz - czet*sz; p[1][1] = -szet*cthet*sz + czet*cz; p[2][1] = -szet*sthet; p[0][2] = -sthet*cz; p[1][2] = -sthet*sz; p[2][2] = cthet; /* Remember the current tranform */ saveepochin = epochin; saveepochout = epochout; } /* Apply the precession formulae */ rar = dtor*rain; decr = dtor*decin; cosa = cos(rar); sina = sin(rar); cosd = cos(decr); sind = sin(decr); r0[0] = cosd*cosa; r0[1] = cosd*sina; r0[2] = sind; pmas = pmain * 15.0; pmds = pmdin; if(vin == 0.0 || pin == 0.0) { rdot0[0] = f*(pmas*(-cosd)*sina + pmds*(-sind)*cosa); rdot0[1] = f*(pmas*cosd*cosa + pmds*(-sind)*sina); rdot0[2] = f*(pmds*cosd); } else { pivelf = 21.094953 * pin * vin; rdot0[0] = f*(pmas*(-cosd)*sina + pmds*(-sind)*cosa+pivelf*r0[0]); rdot0[1] = f*(pmas*cosd*cosa + pmds*(-sind)*sina + pivelf*r0[1]); rdot0[2] = f*(pmds*cosd + pivelf*r0[2]); } for(i=0; i<3; i++) { rdot[i] = p[i][0]*rdot0[0] + p[i][1]*rdot0[1] + p[i][2]*rdot0[2]; r[i] = p[i][0]*(r0[0]+rdot0[0]*delt) + p[i][1]*(r0[1]+rdot0[1]*delt) + p[i][2]*(r0[2]+rdot0[2]*delt); } raoutr = atan2(r[1], r[0]); decoutr = atan2(r[2], sqrt(r[0]*r[0] + r[1]*r[1])); rdiv = sqrt(r[0]*r[0] + r[1]*r[1] + r[2]*r[2]); cosdo = cos(decoutr); sindo = sin(decoutr); cosao = cos(raoutr); sinao = sin(raoutr); duda[0] = -cosdo*sinao; duda[1] = cosdo*cosao; duda[2] = 0.0; dudd[0] = -sindo*cosao; dudd[1] = -sindo*sinao; dudd[2] = cosdo; rdot[0] = rdot[0] / rdiv; rdot[1] = rdot[1] / rdiv; rdot[2] = rdot[2] / rdiv; rapms = (rdot[0]*duda[0] + rdot[1]*duda[1] + rdot[2]*duda[2])/ (f*cosdo*cosdo); decpms = (rdot[0]*dudd[0] + rdot[1]*dudd[1] + rdot[2]*dudd[2])/f; *raout = raoutr * rtod; while(*raout < 0.0) *raout += 360.0; while(*raout > 360.0) *raout -= 360.0; *decout = decoutr * rtod; if(*decout > 90.0) *decout = 90.0; if(*decout < -90.0) *decout = -90.0; *rapm = rapms / 15.0; *decpm = decpms; return; }