Astro with some minor changes to placate Unix.

1 files changed, 81 insertions, 0 deletions

diff --git a/src/cmd/astro/helio.c b/src/cmd/astro/helio.c
new file mode 100644
index 00000000..cb415786
--- /dev/null
+++ b/src/cmd/astro/helio.c
@@ -0,0 +1,81 @@
+#include "astro.h"
+
+void
+helio(void)
+{
+/*
+ *	uses lambda, beta, rad, motion
+ *	sets alpha, delta, rp
+ */
+
+/*
+ *	helio converts from ecliptic heliocentric coordinates
+ *	referred to the mean equinox of date
+ *	to equatorial geocentric coordinates referred to
+ *	the true equator and equinox
+ */
+
+	double xmp, ymp, zmp;
+	double beta2;
+
+/*
+ *	compute geocentric distance of object and
+ *	compute light-time correction (i.i. planetary aberration)
+ */
+
+	xmp = rad*cos(beta)*cos(lambda);
+	ymp = rad*cos(beta)*sin(lambda);
+	zmp = rad*sin(beta);
+	rp = sqrt((xmp+xms)*(xmp+xms) +
+		(ymp+yms)*(ymp+yms) +
+		(zmp+zms)*(zmp+zms));
+	lmb2 = lambda - .0057756e0*rp*motion;
+
+	xmp = rad*cos(beta)*cos(lmb2);
+	ymp = rad*cos(beta)*sin(lmb2);
+	zmp = rad*sin(beta);
+
+/*
+ *	compute annual parallax from the position of the sun
+ */
+
+	xmp += xms;
+	ymp += yms;
+	zmp += zms;
+	rp = sqrt(xmp*xmp + ymp*ymp + zmp*zmp);
+
+/*
+ *	compute annual (i.e. stellar) aberration
+ *	from the orbital velocity of the earth
+ *	(by an incorrect method)
+ */
+
+	xmp -= xdot*rp;
+	ymp -= ydot*rp;
+	zmp -= zdot*rp;
+
+/*
+ *	perform the nutation and so convert from the mean
+ *	equator and equinox to the true
+ */
+
+	lmb2 = atan2(ymp, xmp);
+	beta2 = atan2(zmp, sqrt(xmp*xmp+ymp*ymp));
+	lmb2 += phi;
+
+/*
+ *	change to equatorial coordinates
+ */
+
+	xmp = rp*cos(lmb2)*cos(beta2);
+	ymp = rp*(sin(lmb2)*cos(beta2)*cos(tobliq) - sin(tobliq)*sin(beta2));
+	zmp = rp*(sin(lmb2)*cos(beta2)*sin(tobliq) + cos(tobliq)*sin(beta2));
+
+	alpha = atan2(ymp, xmp);
+	delta = atan2(zmp, sqrt(xmp*xmp+ymp*ymp));
+
+	hp = 8.794e0*radsec/rp;
+	semi /= rp;
+	if(rad > 0 && rad < 2.e5)
+		mag += 2.17*log(rad*rp);
+}