1 #include "astro.h"
2 
3 void
4 star(void)
5 {
6 	double xm, ym, zm, dxm, dym, dzm;
7 	double xx, yx, zx, yy, zy, zz, tau;
8 	double capt0, capt1, capt12, capt13, sl, sb, cl;
9 
10 /*
11  *	remove E-terms of aberration
12  *	except when finding catalog mean places
13  */
14 
15 	alpha += (.341/(3600.*15.))*sin((alpha+11.26)*15.*radian)
16 		  /cos(delta*radian);
17 	delta += (.341/3600.)*cos((alpha+11.26)*15.*radian)
18 		  *sin(delta*radian) - (.029/3600.)*cos(delta*radian);
19 
20 /*
21  *	correct for proper motion
22  */
23 
24 	tau = (eday - epoch)/365.24220;
25 	alpha += tau*da/3600.;
26 	delta += tau*dd/3600.;
27 	alpha *= 15.*radian;
28 	delta *= radian;
29 
30 /*
31  *	convert to rectangular coordinates merely for convenience
32  */
33 
34 	xm = cos(delta)*cos(alpha);
35 	ym = cos(delta)*sin(alpha);
36 	zm = sin(delta);
37 
38 /*
39  *	convert mean places at epoch of startable to current
40  *	epoch (i.e. compute relevant precession)
41  */
42 
43 	capt0 = (epoch - 18262.427)/36524.220e0;
44 	capt1 = (eday - epoch)/36524.220;
45 	capt12 = capt1*capt1;
46 	capt13 = capt12*capt1;
47 
48 	xx = - (.00029696+26.e-8*capt0)*capt12
49 		  - 13.e-8*capt13;
50 	yx =  -(.02234941+1355.e-8*capt0)*capt1
51 		  - 676.e-8*capt12 + 221.e-8*capt13;
52 	zx = -(.00971690-414.e-8*capt0)*capt1
53 		  + 207.e-8*capt12 + 96.e-8*capt13;
54 	yy = - (.00024975+30.e-8*capt0)*capt12
55 		  - 15.e-8*capt13;
56 	zy = -(.00010858+2.e-8*capt0)*capt12;
57 	zz = - (.00004721-4.e-8*capt0)*capt12;
58 
59 	dxm =  xx*xm + yx*ym + zx*zm;
60 	dym = - yx*xm + yy*ym + zy*zm;
61 	dzm = - zx*xm + zy*ym + zz*zm;
62 
63 	xm = xm + dxm;
64 	ym = ym + dym;
65 	zm = zm + dzm;
66 
67 /*
68  *	convert to mean ecliptic system of date
69  */
70 
71 	alpha = atan2(ym, xm);
72 	delta = atan2(zm, sqrt(xm*xm+ym*ym));
73 	cl = cos(delta)*cos(alpha);
74 	sl = cos(delta)*sin(alpha)*cos(obliq) + sin(delta)*sin(obliq);
75 	sb = -cos(delta)*sin(alpha)*sin(obliq) + sin(delta)*cos(obliq);
76 	lambda = atan2(sl, cl);
77 	beta = atan2(sb, sqrt(cl*cl+sl*sl));
78 	rad = 1.e9;
79 	if(px != 0)
80 		rad = 20600/px;
81 	motion = 0;
82 	semi = 0;
83 
84 	helio();
85 	geo();
86 }