added Steve K9AN's sh/moon stuff

[spider.git] / perl / Sun.pm

diff --git a/perl/Sun.pm b/perl/Sun.pm
index 2fe033cd8e42911c37209f430120f402312dea98..759f99489a76199f0e2572f08b39d07ea852850a 100644 (file)
--- a/perl/Sun.pm
+++ b/perl/Sun.pm
@@ -1,4 +1,4 @@
-#!/usr/bin/perl -w
+#/usr/bin/perl -w
 #
 # This module was written by Steve Franke K9AN. 
 # November, 1999.
@@ -169,6 +169,7 @@ sub rise_set
        my ($alpha1,$alpha2,$alpha3,$delta1,$delta2,$delta3);
        my ($m0,$m1,$m2,$theta,$alpha,$delta,$H,$az,$h,$h0,$aznow,$hnow,$corr);
        my ($i,$arg,$argtest,$H0,$alphanow,$deltanow,$distance,$distancenow);
+       my ($ifrac,$ifracnow);
        
        my $julianday=Julian_Day($year,$month,$day);
        my $tt1 = ($julianday-1-2451545)/36525.;
@@ -198,10 +199,10 @@ sub rise_set
        }
 
        if ( $sun0_moon1 == 1 ) {
-               ($alpha1, $delta1, $distance)=get_moon_alpha_delta($tt1);
-               ($alpha2, $delta2, $distance)=get_moon_alpha_delta($tt2);
-               ($alpha3, $delta3, $distance)=get_moon_alpha_delta($tt3);
-               ($alphanow, $deltanow, $distancenow)=get_moon_alpha_delta($ttnow);
+               ($alpha1, $delta1, $distance, $ifrac)=get_moon_alpha_delta($tt1);
+               ($alpha2, $delta2, $distance, $ifrac)=get_moon_alpha_delta($tt2);
+               ($alpha3, $delta3, $distance, $ifrac)=get_moon_alpha_delta($tt3);
+               ($alphanow, $deltanow, $distancenow, $ifracnow)=get_moon_alpha_delta($ttnow);
                $h0=0.7275*$r2d*asin(6378.14/$distancenow)-34./60.;
                $H=$thetanow-$lon-$alphanow;
                $H=reduce_angle_to_360($H);
@@ -315,7 +316,7 @@ sub rise_set
        }
        if ( $sun0_moon1 == 1 ) {
                return (sprintf("%s", $risetime), sprintf("%s",$settime), 
-                               $aznow+180,$hnow, -40*log10($distance/385000) );
+                       $aznow+180,$hnow, -40*log10($distance/385000), $ifracnow );
        }
 }
 sub get_moon_alpha_delta 
@@ -323,6 +324,9 @@ sub get_moon_alpha_delta
        #
        # Calculate the moon's right ascension and declination
        #
+       # As of October 2001, also calculate the illuminated fraction of the 
+       # moon's disk... (why not?)
+       #
        my $tt=shift;
 
        my $Lp=218.3164477+481267.88123421*$tt-
@@ -542,7 +546,20 @@ sub get_moon_alpha_delta
        my $delta=asin(cosdeg($beta)*sindeg($epsilon)*sindeg($lambda)+sindeg($beta)*cosdeg($epsilon))*$r2d;
        $delta = reduce_angle_to_360($delta);
 
-       return ($alpha,$delta,$distance);
+# $phase will be the "moon phase angle" from p. 346 of Meeus' book...
+       my $phase=180.0 - $D - 6.289 *sindeg($Mp)
+                               + 2.100 *sindeg($M)
+                               - 1.274 *sindeg(2.*$D - $Mp)
+                               - 0.658 *sindeg(2.*$D)
+                               - 0.214 *sindeg(2.*$Mp)
+                               - 0.110 *sindeg($D);
+
+# $illum_frac is the fraction of the disk that is illuminated, and will be
+# zero at new moon and 1.0 at full moon.
+
+       my $illum_frac = (1.0 + cosdeg( $phase ))/2.;   
+
+       return ($alpha,$delta,$distance,$illum_frac);
 }
  
 sub get_sun_alpha_delta