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tdetoys/kmoon/phases.cpp

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/* This file is part of the kmoon application with explicit permission by the author
Copyright (C) 1996 Christopher Osburn
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
/*
** jd.c:
** 1996/02/11
**
** Copyright 1996, Christopher Osburn, Lunar Outreach Services,
** Non-commercial usage license granted to all.
**
** convert a Julian Day number to a struct tm
**
** Parameter:
** double jd: Julian day number with fraction of day
**
** Returns:
** struct tm *event_date: Date-time group holding year, month, day, hour,
** and minute of the event
*/
#include <time.h>
#include <stdlib.h>
time_t JDtoDate(double jd, struct tm *event_date)
/* convert a Julian Date to a date-time group */
{
long a, a1, z, b, c, d, e;
double f, day;
struct tm dummy;
if ( !event_date )
event_date = &dummy;
jd += 0.5;
z = (long) jd;
f = jd - z;
if (z < 2299161)
{
a = z;
}
else
{
a1 = (long) ((z - 1867216.25) / 36524.25);
a = z + 1 + a1 - (long)(a1 / 4);
}
b = a + 1524;
c = (long)((b - 122.1) / 365.25);
d = (long)(365.25 * c);
e = (long)((b - d)/30.6001);
day = b - d - (long)(30.6001 * e) + f;
if (e < 14)
{
event_date->tm_mon = (e - 1) - 1;
}
else
{
event_date->tm_mon = (e - 13) - 1;
}
if (event_date->tm_mon > (2 - 1))
{
event_date->tm_year = c - 4716 - 1900;
}
else
{
event_date->tm_year = c - 4715 - 1900;
}
event_date->tm_mday = (int)day;
day -= event_date->tm_mday;
day *= 24;
event_date->tm_hour = (int)day;
day -= event_date->tm_hour;
day *= 60;
event_date->tm_min = (int)day;
day -= event_date->tm_min;
day *= 60;
event_date->tm_sec = (int)day;
event_date->tm_isdst = -1;
return mktime(event_date);
}
double DatetoJD(struct tm *event_date)
/* convert a date-time group to a JD with fraction */
{
int y, m;
double d;
int a, b;
double jd;
y = event_date->tm_year + 1900;
m = event_date->tm_mon + 1;
d = (double)(event_date->tm_mday) + (event_date->tm_hour / 24.0)
+ (event_date->tm_min / 1440.0) + (event_date->tm_sec / 86400.0);
if (m == 1 || m == 2)
{
y--;
m += 12;
}
a = (int)(y / 100);
b = 2 - a + (int)(a / 4);
if (y < 1583)
if ((y < 1582) || (m < 10) || ((m == 10) && (d <= 15)))
b = 0;
jd = (long)(365.25 * (y + 4716)) + (long)(30.6001 * (m+1))
+ d + b - 1524.5;
return jd;
}
/*
** misc.h
** 1996/02/11
**
** Copyright 1996, Christopher Osburn, Lunar Outreach Services,
** Non-commercial usage license granted to all.
**
** Miscellaneous routines for moon phase programs
**
*/
#include <math.h>
double torad(double x)
/* convert x to radians */
{
x = fmod(x, 360.0); /* normalize the angle */
return ((x) * 0.01745329251994329576);
/* and return the result */
}
/*
** moonphase.c
** 1996/02/11
**
** Copyright 1996, Christopher Osburn, Lunar Outreach Services,
** Non-commercial usage license granted to all.
**
** calculate phase of the moon per Meeus Ch. 47
**
** Parameters:
** int lun: phase parameter. This is the number of lunations
** since the New Moon of 2000 January 6.
**
** int phi: another phase parameter, selecting the phase of the
** moon. 0 = New, 1 = First TQtr, 2 = Full, 3 = Last TQtr
**
** Return: Apparent JD of the needed phase
*/
#include <stdio.h>
#include <math.h>
double moonphase(double k, int phi)
{
int i; /* iterator to be named later. Every
program needs an i */
double T; /* time parameter, Julian Centuries since
J2000 */
double JDE; /* Julian Ephemeris Day of phase event */
double E; /* Eccentricity anomaly */
double M; /* Sun's mean anomaly */
double M1; /* Moon's mean anomaly */
double F; /* Moon's argument of latitude */
double O; /* Moon's longitude of ascenfing node */
double A[15]; /* planetary arguments */
double W; /* added correction for quarter phases */
T = k / 1236.85; /* (47.3) */
/* this is the first approximation. all else is for style points! */
JDE = 2451550.09765 + (29.530588853 * k) /* (47.1) */
+ T * T * (0.0001337 + T * (-0.000000150 + 0.00000000073 * T));
/* these are correction parameters used below */
E = 1.0 /* (45.6) */
+ T * (-0.002516 + -0.0000074 * T);
M = 2.5534 + 29.10535669 * k /* (47.4) */
+ T * T * (-0.0000218 + -0.00000011 * T);
M1 = 201.5643 + 385.81693528 * k /* (47.5) */
+ T * T * (0.0107438 + T * (0.00001239 + -0.000000058 * T));
F = 160.7108 + 390.67050274 * k /* (47.6) */
+ T * T * (-0.0016341 * T * (-0.00000227 + 0.000000011 * T));
O = 124.7746 - 1.56375580 * k /* (47.7) */
+ T * T * (0.0020691 + 0.00000215 * T);
/* planetary arguments */
A[0] = 0; /* unused! */
A[1] = 299.77 + 0.107408 * k - 0.009173 * T * T;
A[2] = 251.88 + 0.016321 * k;
A[3] = 251.83 + 26.651886 * k;
A[4] = 349.42 + 36.412478 * k;
A[5] = 84.66 + 18.206239 * k;
A[6] = 141.74 + 53.303771 * k;
A[7] = 207.14 + 2.453732 * k;
A[8] = 154.84 + 7.306860 * k;
A[9] = 34.52 + 27.261239 * k;
A[10] = 207.19 + 0.121824 * k;
A[11] = 291.34 + 1.844379 * k;
A[12] = 161.72 + 24.198154 * k;
A[13] = 239.56 + 25.513099 * k;
A[14] = 331.55 + 3.592518 * k;
/* all of the above crap must be made into radians!!! */
/* except for E... */
M = torad(M);
M1 = torad(M1);
F = torad(F);
O = torad(O);
/* all those planetary arguments, too! */
for (i=1; i<=14; i++)
A[i] = torad(A[i]);
/* ok, we have all the parameters, let's apply them to the JDE.
(remember the JDE? this is a program about the JDE...) */
switch(phi)
{
/* a special case for each different phase. NOTE!,
I'm not treating these in a 0123 order!!! Pay
attention, there, you! */
case 0: /* New Moon */
JDE = JDE
- 0.40720 * sin (M1)
+ 0.17241 * E * sin (M)
+ 0.01608 * sin (2.0 * M1)
+ 0.01039 * sin (2.0 * F)
+ 0.00739 * E * sin (M1 - M)
- 0.00514 * E * sin (M1 + M)
+ 0.00208 * E * E * sin (2.0 * M)
- 0.00111 * sin (M1 - 2.0 * F)
- 0.00057 * sin (M1 + 2.0 * F)
+ 0.00056 * E * sin (2.0 * M1 + M)
- 0.00042 * sin (3.0 * M1)
+ 0.00042 * E * sin (M + 2.0 * F)
+ 0.00038 * E * sin (M - 2.0 * F)
- 0.00024 * E * sin (2.0 * M1 - M)
- 0.00017 * sin (O)
- 0.00007 * sin (M1 + 2.0 * M)
+ 0.00004 * sin (2.0 * M1 - 2.0 * F)
+ 0.00004 * sin (3.0 * M)
+ 0.00003 * sin (M1 + M - 2.0 * F)
+ 0.00003 * sin (2.0 * M1 + 2.0 * F)
- 0.00003 * sin (M1 + M + 2.0 * F)
+ 0.00003 * sin (M1 - M + 2.0 * F)
- 0.00002 * sin (M1 - M - 2.0 * F)
- 0.00002 * sin (3.0 * M1 + M)
+ 0.00002 * sin (4.0 * M1);
break;
case 2: /* Full Moon */
JDE = JDE
- 0.40614 * sin (M1)
+ 0.17302 * E * sin (M)
+ 0.01614 * sin (2.0 * M1)
+ 0.01043 * sin (2.0 * F)
+ 0.00734 * E * sin (M1 - M)
- 0.00515 * E * sin (M1 + M)
+ 0.00209 * E * E * sin (2.0 * M)
- 0.00111 * sin (M1 - 2.0 * F)
- 0.00057 * sin (M1 + 2.0 * F)
+ 0.00056 * E * sin (2.0 * M1 + M)
- 0.00042 * sin (3.0 * M1)
+ 0.00042 * E * sin (M + 2.0 * F)
+ 0.00038 * E * sin (M - 2.0 * F)
- 0.00024 * E * sin (2.0 * M1 - M)
- 0.00017 * sin (O)
- 0.00007 * sin (M1 + 2.0 * M)
+ 0.00004 * sin (2.0 * M1 - 2.0 * F)
+ 0.00004 * sin (3.0 * M)
+ 0.00003 * sin (M1 + M - 2.0 * F)
+ 0.00003 * sin (2.0 * M1 + 2.0 * F)
- 0.00003 * sin (M1 + M + 2.0 * F)
+ 0.00003 * sin (M1 - M + 2.0 * F)
- 0.00002 * sin (M1 - M - 2.0 * F)
- 0.00002 * sin (3.0 * M1 + M)
+ 0.00002 * sin (4.0 * M1);
break;
case 1: /* First Quarter */
case 3: /* Last Quarter */
JDE = JDE
- 0.62801 * sin (M1)
+ 0.17172 * E * sin (M)
- 0.01183 * E * sin (M1 + M)
+ 0.00862 * sin (2.0 * M1)
+ 0.00804 * sin (2.0 * F)
+ 0.00454 * E * sin (M1 - M)
+ 0.00204 * E * E * sin (2.0 * M)
- 0.00180 * sin (M1 - 2.0 * F)
- 0.00070 * sin (M1 + 2.0 * F)
- 0.00040 * sin (3.0 * M1)
- 0.00034 * E * sin (2.0 * M1 - M)
+ 0.00032 * E * sin (M + 2.0 * F)
+ 0.00032 * E * sin (M - 2.0 * F)
- 0.00028 * E * E * sin (M1 + 2.0 * M)
+ 0.00027 * E * sin (2.0 * M1 + M)
- 0.00017 * sin (O)
- 0.00005 * sin (M1 - M - 2.0 * F)
+ 0.00004 * sin (2.0 * M1 + 2.0 * F)
- 0.00004 * sin (M1 + M + 2.0 * F)
+ 0.00004 * sin (M1 - 2.0 * M)
+ 0.00003 * sin (M1 + M - 2.0 * F)
+ 0.00003 * sin (3.0 * M)
+ 0.00002 * sin (2.0 * M1 - 2.0 * F)
+ 0.00002 * sin (M1 - M + 2.0 * F)
- 0.00002 * sin (3.0 * M1 + M);
W = 0.00306
- 0.00038 * E * cos(M)
+ 0.00026 * cos(M1)
- 0.00002 * cos(M1 - M)
+ 0.00002 * cos(M1 + M)
+ 0.00002 * cos(2.0 * F);
if (phi == 3)
W = -W;
JDE += W;
break;
default: /* oops! */
fprintf(stderr, "The Moon has exploded!\n");
exit(1);
break; /* unexecuted code */
}
/* now there are some final correction to everything */
JDE = JDE
+ 0.000325 * sin(A[1])
+ 0.000165 * sin(A[2])
+ 0.000164 * sin(A[3])
+ 0.000126 * sin(A[4])
+ 0.000110 * sin(A[5])
+ 0.000062 * sin(A[6])
+ 0.000060 * sin(A[7])
+ 0.000056 * sin(A[8])
+ 0.000047 * sin(A[9])
+ 0.000042 * sin(A[10])
+ 0.000040 * sin(A[11])
+ 0.000037 * sin(A[12])
+ 0.000035 * sin(A[13])
+ 0.000023 * sin(A[14]);
return JDE;
}
#define LUNATION_OFFSET 953
double moonphasebylunation(int lun, int phi)
{
double k;
k = lun - LUNATION_OFFSET + phi / 4.0;
return moonphase(k, phi);
}
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