/*
JavaScript version
Copyright 2011 Glad Deschrijver <glad.deschrijver@gmail.com>
with the same license as below.
*/
/*
This file is part of the kmoon application with explicit permission by the author
Copyright 1996 Christopher Osburn <chris@speakeasy.org>
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 General Public License
along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
.pragma library
/*
** jd.c:
** 1996/02/11
**
** Copyright 1996, Christopher Osburn, Lunar Outreach Services, <chris@speakeasy.org>
** 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
*/
function JDtoDate(jd) // convert a Julian Date to a date-time group
{
var a, a1, z, b, c, d, e;
var f, day;
var event_date = new Date();
jd += 0.5;
z = Math.floor(jd);
f = jd - z;
if (z < 2299161)
{
a = z;
}
else
{
a1 = Math.floor((z - 1867216.25) / 36524.25);
a = z + 1 + a1 - Math.floor(a1 / 4);
}
b = a + 1524;
c = Math.floor((b - 122.1) / 365.25);
d = Math.floor(365.25 * c);
e = Math.floor((b - d)/30.6001);
day = b - d - Math.floor(30.6001 * e) + f;
event_date.setDate(1); // dirty hack, otherwise if today is the 31st of a month and the month below is set to a month with < 31 days, then the month is shifted to the next month, e.g. Feb 31 becomes Mar 2; the correct day is set further below
if (e < 14)
event_date.setMonth((e - 1) - 1);
else
event_date.setMonth((e - 13) - 1);
if (event_date.getMonth() > (2 - 1))
event_date.setFullYear(c - 4716);
else
event_date.setFullYear(c - 4715);
event_date.setDate(Math.floor(day));
day -= event_date.getDate();
day *= 24;
event_date.setHours(Math.floor(day));
day -= event_date.getHours();
day *= 60;
event_date.setMinutes(Math.floor(day));
day -= event_date.getMinutes();
day *= 60;
event_date.setSeconds(Math.floor(day));
return event_date;
}
function DatetoJD(event_date) // convert a date-time group to a JD with fraction
{
var y, m;
var d;
var a, b;
var jd;
y = event_date.getFullYear();
m = event_date.getMonth() + 1;
d = event_date.getDate() + (event_date.getHours() / 24.0)
+ (event_date.getMinutes() / 1440.0)
+ (event_date.getSeconds() / 86400.0);
if (m == 1 || m == 2)
{
y--;
m += 12;
}
a = Math.floor(y / 100);
b = 2 - a + Math.floor(a / 4);
if (y < 1583)
if ((y < 1582) || (m < 10) || ((m == 10) && (d <= 15)))
b = 0;
jd = Math.floor(365.25 * (y + 4716)) + Math.floor(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
**
*/
function fmod(x, y)
{
var n = ((x > 0 && y > 0) || (x < 0 && y < 0)) ? Math.floor(x / y) : Math.ceil(x / y);
return x - n * y;
}
function torad(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 Qtr, 2 = Full, 3 = Last Qtr
**
** Return: Apparent JD of the needed phase
*/
function moonphase(k, phi)
{
var i; // iterator to be named later. Every program needs an i
var T; // time parameter, Julian Centuries since J2000
var JDE; // Julian Ephemeris Day of phase event
var E; // Eccentricity anomaly
var M; // Sun's mean anomaly
var M1; // Moon's mean anomaly
var F; // Moon's argument of latitude
var O; // Moon's longitude of ascending node
var A = new Array(); // planetary arguments
var 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 * Math.sin(M1)
+ 0.17241 * E * Math.sin(M)
+ 0.01608 * Math.sin(2.0 * M1)
+ 0.01039 * Math.sin(2.0 * F)
+ 0.00739 * E * Math.sin(M1 - M)
- 0.00514 * E * Math.sin(M1 + M)
+ 0.00208 * E * E * Math.sin(2.0 * M)
- 0.00111 * Math.sin(M1 - 2.0 * F)
- 0.00057 * Math.sin(M1 + 2.0 * F)
+ 0.00056 * E * Math.sin(2.0 * M1 + M)
- 0.00042 * Math.sin(3.0 * M1)
+ 0.00042 * E * Math.sin(M + 2.0 * F)
+ 0.00038 * E * Math.sin(M - 2.0 * F)
- 0.00024 * E * Math.sin(2.0 * M1 - M)
- 0.00017 * Math.sin(O)
- 0.00007 * Math.sin(M1 + 2.0 * M)
+ 0.00004 * Math.sin(2.0 * M1 - 2.0 * F)
+ 0.00004 * Math.sin(3.0 * M)
+ 0.00003 * Math.sin(M1 + M - 2.0 * F)
+ 0.00003 * Math.sin(2.0 * M1 + 2.0 * F)
- 0.00003 * Math.sin(M1 + M + 2.0 * F)
+ 0.00003 * Math.sin(M1 - M + 2.0 * F)
- 0.00002 * Math.sin(M1 - M - 2.0 * F)
- 0.00002 * Math.sin(3.0 * M1 + M)
+ 0.00002 * Math.sin(4.0 * M1);
break;
case 2: // Full Moon
JDE = JDE
- 0.40614 * Math.sin(M1)
+ 0.17302 * E * Math.sin(M)
+ 0.01614 * Math.sin(2.0 * M1)
+ 0.01043 * Math.sin(2.0 * F)
+ 0.00734 * E * Math.sin(M1 - M)
- 0.00515 * E * Math.sin(M1 + M)
+ 0.00209 * E * E * Math.sin(2.0 * M)
- 0.00111 * Math.sin(M1 - 2.0 * F)
- 0.00057 * Math.sin(M1 + 2.0 * F)
+ 0.00056 * E * Math.sin(2.0 * M1 + M)
- 0.00042 * Math.sin(3.0 * M1)
+ 0.00042 * E * Math.sin(M + 2.0 * F)
+ 0.00038 * E * Math.sin(M - 2.0 * F)
- 0.00024 * E * Math.sin(2.0 * M1 - M)
- 0.00017 * Math.sin(O)
- 0.00007 * Math.sin(M1 + 2.0 * M)
+ 0.00004 * Math.sin(2.0 * M1 - 2.0 * F)
+ 0.00004 * Math.sin(3.0 * M)
+ 0.00003 * Math.sin(M1 + M - 2.0 * F)
+ 0.00003 * Math.sin(2.0 * M1 + 2.0 * F)
- 0.00003 * Math.sin(M1 + M + 2.0 * F)
+ 0.00003 * Math.sin(M1 - M + 2.0 * F)
- 0.00002 * Math.sin(M1 - M - 2.0 * F)
- 0.00002 * Math.sin(3.0 * M1 + M)
+ 0.00002 * Math.sin(4.0 * M1);
break;
case 1: // First Quarter
case 3: // Last Quarter
JDE = JDE
- 0.62801 * Math.sin(M1)
+ 0.17172 * E * Math.sin(M)
- 0.01183 * E * Math.sin(M1 + M)
+ 0.00862 * Math.sin(2.0 * M1)
+ 0.00804 * Math.sin(2.0 * F)
+ 0.00454 * E * Math.sin(M1 - M)
+ 0.00204 * E * E * Math.sin(2.0 * M)
- 0.00180 * Math.sin(M1 - 2.0 * F)
- 0.00070 * Math.sin(M1 + 2.0 * F)
- 0.00040 * Math.sin(3.0 * M1)
- 0.00034 * E * Math.sin(2.0 * M1 - M)
+ 0.00032 * E * Math.sin(M + 2.0 * F)
+ 0.00032 * E * Math.sin(M - 2.0 * F)
- 0.00028 * E * E * Math.sin(M1 + 2.0 * M)
+ 0.00027 * E * Math.sin(2.0 * M1 + M)
- 0.00017 * Math.sin(O)
- 0.00005 * Math.sin(M1 - M - 2.0 * F)
+ 0.00004 * Math.sin(2.0 * M1 + 2.0 * F)
- 0.00004 * Math.sin(M1 + M + 2.0 * F)
+ 0.00004 * Math.sin(M1 - 2.0 * M)
+ 0.00003 * Math.sin(M1 + M - 2.0 * F)
+ 0.00003 * Math.sin(3.0 * M)
+ 0.00002 * Math.sin(2.0 * M1 - 2.0 * F)
+ 0.00002 * Math.sin(M1 - M + 2.0 * F)
- 0.00002 * Math.sin(3.0 * M1 + M);
W = 0.00306
- 0.00038 * E * Math.cos(M)
+ 0.00026 * Math.cos(M1)
- 0.00002 * Math.cos(M1 - M)
+ 0.00002 * Math.cos(M1 + M)
+ 0.00002 * Math.cos(2.0 * F);
if (phi == 3)
W = -W;
JDE += W;
break;
default: // oops!
console.log("The Moon has exploded!");
exit(1);
break; // unexecuted code
}
// now there are some final correction to everything
JDE = JDE
+ 0.000325 * Math.sin(A[1])
+ 0.000165 * Math.sin(A[2])
+ 0.000164 * Math.sin(A[3])
+ 0.000126 * Math.sin(A[4])
+ 0.000110 * Math.sin(A[5])
+ 0.000062 * Math.sin(A[6])
+ 0.000060 * Math.sin(A[7])
+ 0.000056 * Math.sin(A[8])
+ 0.000047 * Math.sin(A[9])
+ 0.000042 * Math.sin(A[10])
+ 0.000040 * Math.sin(A[11])
+ 0.000037 * Math.sin(A[12])
+ 0.000035 * Math.sin(A[13])
+ 0.000023 * Math.sin(A[14]);
return JDE;
}
//var LUNATION_OFFSET = 953; // original value, I (Glad) don't know why it was chosen as it slows down the startup of the plasmoid
//var LUNATION_OFFSET = -124; // set lunation start in 2010 (faster startup than with the above)
var LUNATION_OFFSET = 0; // a reasonable start lunation is calculated in lunacalc.js
function moonphasebylunation(lun, phi)
{
var k = lun - LUNATION_OFFSET + phi / 4.0;
return moonphase(k, phi);
}