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dakkar/moon.pl

Created July 17, 2019 22:28
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Dates of Easter according to the International Fixed Calendar
Raw
moon.pl
#!/usr/bin/env perl
use 5.024;
use strict;
use warnings;
use experimental 'signatures';
use Astro::MoonPhase ();
use DateTime;
use DateTime::Event::Easter;
# IFC = International Fixed Calendar
# converts a datetime into a IFC date
sub to_ifc($dt) {
my $doy = $dt->day_of_year - 1; # method result starts at 1
my $IFC_month = 1 + int($doy / 28); # all months are 28 days
my $IFC_day = $doy % 28 + 1;
my $IFC_dow = $doy % 7; # all months start on Sunday
my $IFC_dow_name = [qw(Sun Mon Tue Wed Thu Fri Sat)]->[$IFC_dow];
return {
month => $IFC_month,
day => $IFC_day,
dow => $IFC_dow,
dow_name => $IFC_dow_name
};
}
sub first_ifc_sunday_after($start_dt) {
return undef unless $start_dt;
for my $days (0..7) { # we'll hit a sunday in 8 days!
my $dt = $start_dt->clone->add(days => $days);
my $ifc = to_ifc($dt);
return $dt if $ifc->{dow} == 0
}
return undef;
}
sub format_date($dt) {
return "none?" unless $dt;
my $normal_date = $dt->strftime('%m-%d %a');
my $ifc_date = to_ifc($dt);
return sprintf '%s (%03d = %02d-%02d %s)',
$normal_date,
$dt->doy,
@{$ifc_date}{qw(month day dow_name)};
}
sub full_moon_between($start_dt,$stop_dt) {
# code copied from Astro::MoonPhase documentation
my ($phase,@times) = Astro::MoonPhase::phaselist(
$start_dt->epoch,
# phaselist excludes the last day, let's add one
$stop_dt->epoch + 86400,
);
while (@times) {
if ($phase == 2) { # full moon
return DateTime->from_epoch( epoch => $times[0] );
}
shift @times;
$phase = ($phase + 1) % 4;
}
return undef;
}
# print date of Catholic Easter in Gregorian calendar and IFC
sub for_year($year) {
my $solstice = DateTime->new(
year => $year,
month => 3,
day => 20, # good enough
hour => 12,
time_zone => 'Europe/Rome',
);
my $easter_sunday = DateTime::Event::Easter->new(
easter => 'western',
day => 'Easter Sunday',
as => 'point',
)->following($solstice);
my $full_moon = full_moon_between($solstice, $easter_sunday);
my $IFC_easter = first_ifc_sunday_after($full_moon);
printf "%04d: full moon: %s easter: %s ifc easter: %s\n",
$year,
format_date($full_moon),
format_date($easter_sunday),
format_date($IFC_easter),
;
}
for my $year (1900..2000) {
for_year($year);
}
Raw
output.txt
1900: full moon: 04-15 Sun (105 = 04-21 Sat) easter: 04-15 Sun (105 = 04-21 Sat) ifc easter: 04-16 Mon (106 = 04-22 Sun)
1901: full moon: 04-04 Thu (094 = 04-10 Tue) easter: 04-07 Sun (097 = 04-13 Fri) ifc easter: 04-09 Tue (099 = 04-15 Sun)
1902: full moon: 03-24 Mon (083 = 03-27 Fri) easter: 03-30 Sun (089 = 04-05 Thu) ifc easter: 03-26 Wed (085 = 04-01 Sun)
1903: full moon: 04-12 Sun (102 = 04-18 Wed) easter: 04-12 Sun (102 = 04-18 Wed) ifc easter: 04-16 Thu (106 = 04-22 Sun)
1904: full moon: 03-31 Thu (091 = 04-07 Sat) easter: 04-03 Sun (094 = 04-10 Tue) ifc easter: 04-01 Fri (092 = 04-08 Sun)
1905: full moon: 03-21 Tue (080 = 03-24 Tue) easter: 04-23 Sun (113 = 05-01 Sun) ifc easter: 03-26 Sun (085 = 04-01 Sun)
1906: full moon: 04-09 Mon (099 = 04-15 Sun) easter: 04-15 Sun (105 = 04-21 Sat) ifc easter: 04-09 Mon (099 = 04-15 Sun)
1907: full moon: 03-29 Fri (088 = 04-04 Wed) easter: 03-31 Sun (090 = 04-06 Fri) ifc easter: 04-02 Tue (092 = 04-08 Sun)
1908: full moon: 04-16 Thu (107 = 04-23 Mon) easter: 04-19 Sun (110 = 04-26 Thu) ifc easter: 04-22 Wed (113 = 05-01 Sun)
1909: full moon: 04-05 Mon (095 = 04-11 Wed) easter: 04-11 Sun (101 = 04-17 Tue) ifc easter: 04-09 Fri (099 = 04-15 Sun)
1910: full moon: 03-25 Fri (084 = 03-28 Sat) easter: 03-27 Sun (086 = 04-02 Mon) ifc easter: 03-26 Sat (085 = 04-01 Sun)
1911: full moon: 04-13 Thu (103 = 04-19 Thu) easter: 04-16 Sun (106 = 04-22 Sun) ifc easter: 04-16 Sun (106 = 04-22 Sun)
1912: full moon: 04-01 Mon (092 = 04-08 Sun) easter: 04-07 Sun (098 = 04-14 Sat) ifc easter: 04-01 Mon (092 = 04-08 Sun)
1913: full moon: 03-22 Sat (081 = 03-25 Wed) easter: 03-23 Sun (082 = 03-26 Thu) ifc easter: 03-26 Wed (085 = 04-01 Sun)
1914: full moon: 04-10 Fri (100 = 04-16 Mon) easter: 04-12 Sun (102 = 04-18 Wed) ifc easter: 04-16 Thu (106 = 04-22 Sun)
1915: full moon: 03-31 Wed (090 = 04-06 Fri) easter: 04-04 Sun (094 = 04-10 Tue) ifc easter: 04-02 Fri (092 = 04-08 Sun)
1916: full moon: 04-18 Tue (109 = 04-25 Wed) easter: 04-23 Sun (114 = 05-02 Mon) ifc easter: 04-22 Sat (113 = 05-01 Sun)
1917: full moon: 04-07 Sat (097 = 04-13 Fri) easter: 04-08 Sun (098 = 04-14 Sat) ifc easter: 04-09 Mon (099 = 04-15 Sun)
1918: full moon: 03-27 Wed (086 = 04-02 Mon) easter: 03-31 Sun (090 = 04-06 Fri) ifc easter: 04-02 Tue (092 = 04-08 Sun)
1919: full moon: 04-15 Tue (105 = 04-21 Sat) easter: 04-20 Sun (110 = 04-26 Thu) ifc easter: 04-16 Wed (106 = 04-22 Sun)
1920: full moon: 04-03 Sat (094 = 04-10 Tue) easter: 04-04 Sun (095 = 04-11 Wed) ifc easter: 04-08 Thu (099 = 04-15 Sun)
1921: full moon: 03-23 Wed (082 = 03-26 Thu) easter: 03-27 Sun (086 = 04-02 Mon) ifc easter: 03-26 Sat (085 = 04-01 Sun)
1922: full moon: 04-11 Tue (101 = 04-17 Tue) easter: 04-16 Sun (106 = 04-22 Sun) ifc easter: 04-16 Sun (106 = 04-22 Sun)
1923: full moon: 04-01 Sun (091 = 04-07 Sat) easter: 04-01 Sun (091 = 04-07 Sat) ifc easter: 04-02 Mon (092 = 04-08 Sun)
1924: full moon: 03-21 Fri (081 = 03-25 Wed) easter: 04-20 Sun (111 = 04-27 Fri) ifc easter: 03-25 Tue (085 = 04-01 Sun)
1925: full moon: 04-09 Thu (099 = 04-15 Sun) easter: 04-12 Sun (102 = 04-18 Wed) ifc easter: 04-09 Thu (099 = 04-15 Sun)
1926: full moon: 03-29 Mon (088 = 04-04 Wed) easter: 04-04 Sun (094 = 04-10 Tue) ifc easter: 04-02 Fri (092 = 04-08 Sun)
1927: full moon: 04-17 Sun (107 = 04-23 Mon) easter: 04-17 Sun (107 = 04-23 Mon) ifc easter: 04-23 Sat (113 = 05-01 Sun)
1928: full moon: 04-05 Thu (096 = 04-12 Thu) easter: 04-08 Sun (099 = 04-15 Sun) ifc easter: 04-08 Sun (099 = 04-15 Sun)
1929: full moon: 03-25 Mon (084 = 03-28 Sat) easter: 03-31 Sun (090 = 04-06 Fri) ifc easter: 03-26 Tue (085 = 04-01 Sun)
1930: full moon: 04-13 Sun (103 = 04-19 Thu) easter: 04-20 Sun (110 = 04-26 Thu) ifc easter: 04-16 Wed (106 = 04-22 Sun)
1931: full moon: 04-02 Thu (092 = 04-08 Sun) easter: 04-05 Sun (095 = 04-11 Wed) ifc easter: 04-02 Thu (092 = 04-08 Sun)
1932: full moon: 03-22 Tue (082 = 03-26 Thu) easter: 03-27 Sun (087 = 04-03 Tue) ifc easter: 03-25 Fri (085 = 04-01 Sun)
1933: full moon: 04-10 Mon (100 = 04-16 Mon) easter: 04-16 Sun (106 = 04-22 Sun) ifc easter: 04-16 Sun (106 = 04-22 Sun)
1934: full moon: 03-31 Sat (090 = 04-06 Fri) easter: 04-01 Sun (091 = 04-07 Sat) ifc easter: 04-02 Mon (092 = 04-08 Sun)
1935: full moon: 04-18 Thu (108 = 04-24 Tue) easter: 04-21 Sun (111 = 04-27 Fri) ifc easter: 04-23 Tue (113 = 05-01 Sun)
1936: full moon: 04-06 Mon (097 = 04-13 Fri) easter: 04-12 Sun (103 = 04-19 Thu) ifc easter: 04-08 Wed (099 = 04-15 Sun)
1937: full moon: 03-26 Fri (085 = 04-01 Sun) easter: 03-28 Sun (087 = 04-03 Tue) ifc easter: 03-26 Fri (085 = 04-01 Sun)
1938: full moon: 04-14 Thu (104 = 04-20 Fri) easter: 04-17 Sun (107 = 04-23 Mon) ifc easter: 04-16 Sat (106 = 04-22 Sun)
1939: full moon: 04-04 Tue (094 = 04-10 Tue) easter: 04-09 Sun (099 = 04-15 Sun) ifc easter: 04-09 Sun (099 = 04-15 Sun)
1940: full moon: 03-23 Sat (083 = 03-27 Fri) easter: 03-24 Sun (084 = 03-28 Sat) ifc easter: 03-25 Mon (085 = 04-01 Sun)
1941: full moon: 04-11 Fri (101 = 04-17 Tue) easter: 04-13 Sun (103 = 04-19 Thu) ifc easter: 04-16 Wed (106 = 04-22 Sun)
1942: full moon: 04-01 Wed (091 = 04-07 Sat) easter: 04-05 Sun (095 = 04-11 Wed) ifc easter: 04-02 Thu (092 = 04-08 Sun)
1943: full moon: 03-21 Sun (080 = 03-24 Tue) easter: 04-25 Sun (115 = 05-03 Tue) ifc easter: 03-26 Fri (085 = 04-01 Sun)
1944: full moon: 04-08 Sat (099 = 04-15 Sun) easter: 04-09 Sun (100 = 04-16 Mon) ifc easter: 04-08 Sat (099 = 04-15 Sun)
1945: full moon: 03-28 Wed (087 = 04-03 Tue) easter: 04-01 Sun (091 = 04-07 Sat) ifc easter: 04-02 Mon (092 = 04-08 Sun)
1946: full moon: 04-16 Tue (106 = 04-22 Sun) easter: 04-21 Sun (111 = 04-27 Fri) ifc easter: 04-16 Tue (106 = 04-22 Sun)
1947: full moon: 04-05 Sat (095 = 04-11 Wed) easter: 04-06 Sun (096 = 04-12 Thu) ifc easter: 04-09 Wed (099 = 04-15 Sun)
1948: full moon: 03-25 Thu (085 = 04-01 Sun) easter: 03-28 Sun (088 = 04-04 Wed) ifc easter: 03-25 Thu (085 = 04-01 Sun)
1949: full moon: 04-13 Wed (103 = 04-19 Thu) easter: 04-17 Sun (107 = 04-23 Mon) ifc easter: 04-16 Sat (106 = 04-22 Sun)
1950: full moon: 04-02 Sun (092 = 04-08 Sun) easter: 04-09 Sun (099 = 04-15 Sun) ifc easter: 04-02 Sun (092 = 04-08 Sun)
1951: full moon: 03-23 Fri (082 = 03-26 Thu) easter: 03-25 Sun (084 = 03-28 Sat) ifc easter: 03-26 Mon (085 = 04-01 Sun)
1952: full moon: 04-10 Thu (101 = 04-17 Tue) easter: 04-13 Sun (104 = 04-20 Fri) ifc easter: 04-15 Tue (106 = 04-22 Sun)
1953: full moon: 03-30 Mon (089 = 04-05 Thu) easter: 04-05 Sun (095 = 04-11 Wed) ifc easter: 04-02 Thu (092 = 04-08 Sun)
1954: full moon: 04-18 Sun (108 = 04-24 Tue) easter: 04-18 Sun (108 = 04-24 Tue) ifc easter: 04-23 Fri (113 = 05-01 Sun)
1955: full moon: 04-07 Thu (097 = 04-13 Fri) easter: 04-10 Sun (100 = 04-16 Mon) ifc easter: 04-09 Sat (099 = 04-15 Sun)
1956: full moon: 03-26 Mon (086 = 04-02 Mon) easter: 04-01 Sun (092 = 04-08 Sun) ifc easter: 04-01 Sun (092 = 04-08 Sun)
1957: full moon: 04-14 Sun (104 = 04-20 Fri) easter: 04-21 Sun (111 = 04-27 Fri) ifc easter: 04-16 Tue (106 = 04-22 Sun)
1958: full moon: 04-04 Fri (094 = 04-10 Tue) easter: 04-06 Sun (096 = 04-12 Thu) ifc easter: 04-09 Wed (099 = 04-15 Sun)
1959: full moon: 03-24 Tue (083 = 03-27 Fri) easter: 03-29 Sun (088 = 04-04 Wed) ifc easter: 03-26 Thu (085 = 04-01 Sun)
1960: full moon: 04-11 Mon (102 = 04-18 Wed) easter: 04-17 Sun (108 = 04-24 Tue) ifc easter: 04-15 Fri (106 = 04-22 Sun)
1961: full moon: 04-01 Sat (091 = 04-07 Sat) easter: 04-02 Sun (092 = 04-08 Sun) ifc easter: 04-02 Sun (092 = 04-08 Sun)
1962: full moon: 03-21 Wed (080 = 03-24 Tue) easter: 04-22 Sun (112 = 04-28 Sat) ifc easter: 03-26 Mon (085 = 04-01 Sun)
1963: full moon: 04-09 Tue (099 = 04-15 Sun) easter: 04-14 Sun (104 = 04-20 Fri) ifc easter: 04-09 Tue (099 = 04-15 Sun)
1964: full moon: 03-28 Sat (088 = 04-04 Wed) easter: 03-29 Sun (089 = 04-05 Thu) ifc easter: 04-01 Wed (092 = 04-08 Sun)
1965: full moon: 04-15 Thu (105 = 04-21 Sat) easter: 04-18 Sun (108 = 04-24 Tue) ifc easter: 04-16 Fri (106 = 04-22 Sun)
1966: full moon: 04-05 Tue (095 = 04-11 Wed) easter: 04-10 Sun (100 = 04-16 Mon) ifc easter: 04-09 Sat (099 = 04-15 Sun)
1967: full moon: 03-26 Sun (085 = 04-01 Sun) easter: 03-26 Sun (085 = 04-01 Sun) ifc easter: 03-26 Sun (085 = 04-01 Sun)
1968: full moon: 04-13 Sat (104 = 04-20 Fri) easter: 04-14 Sun (105 = 04-21 Sat) ifc easter: 04-15 Mon (106 = 04-22 Sun)
1969: full moon: 04-02 Wed (092 = 04-08 Sun) easter: 04-06 Sun (096 = 04-12 Thu) ifc easter: 04-02 Wed (092 = 04-08 Sun)
1970: full moon: 03-23 Mon (082 = 03-26 Thu) easter: 03-29 Sun (088 = 04-04 Wed) ifc easter: 03-26 Thu (085 = 04-01 Sun)
1971: full moon: 04-10 Sat (100 = 04-16 Mon) easter: 04-11 Sun (101 = 04-17 Tue) ifc easter: 04-16 Fri (106 = 04-22 Sun)
1972: full moon: 03-29 Wed (089 = 04-05 Thu) easter: 04-02 Sun (093 = 04-09 Mon) ifc easter: 04-01 Sat (092 = 04-08 Sun)
1973: full moon: 04-17 Tue (107 = 04-23 Mon) easter: 04-22 Sun (112 = 04-28 Sat) ifc easter: 04-23 Mon (113 = 05-01 Sun)
1974: full moon: 04-06 Sat (096 = 04-12 Thu) easter: 04-14 Sun (104 = 04-20 Fri) ifc easter: 04-09 Tue (099 = 04-15 Sun)
1975: full moon: 03-27 Thu (086 = 04-02 Mon) easter: 03-30 Sun (089 = 04-05 Thu) ifc easter: 04-02 Wed (092 = 04-08 Sun)
1976: full moon: 04-14 Wed (105 = 04-21 Sat) easter: 04-18 Sun (109 = 04-25 Wed) ifc easter: 04-15 Thu (106 = 04-22 Sun)
1977: full moon: 04-04 Mon (094 = 04-10 Tue) easter: 04-10 Sun (100 = 04-16 Mon) ifc easter: 04-09 Sat (099 = 04-15 Sun)
1978: full moon: 03-24 Fri (083 = 03-27 Fri) easter: 03-26 Sun (085 = 04-01 Sun) ifc easter: 03-26 Sun (085 = 04-01 Sun)
1979: full moon: 04-12 Thu (102 = 04-18 Wed) easter: 04-15 Sun (105 = 04-21 Sat) ifc easter: 04-16 Mon (106 = 04-22 Sun)
1980: full moon: 03-31 Mon (091 = 04-07 Sat) easter: 04-06 Sun (097 = 04-13 Fri) ifc easter: 04-01 Tue (092 = 04-08 Sun)
1981: full moon: 03-20 Fri (079 = 03-23 Mon) easter: 04-19 Sun (109 = 04-25 Wed) ifc easter: 03-26 Thu (085 = 04-01 Sun)
1982: full moon: 04-08 Thu (098 = 04-14 Sat) easter: 04-11 Sun (101 = 04-17 Tue) ifc easter: 04-09 Fri (099 = 04-15 Sun)
1983: full moon: 03-28 Mon (087 = 04-03 Tue) easter: 04-03 Sun (093 = 04-09 Mon) ifc easter: 04-02 Sat (092 = 04-08 Sun)
1984: full moon: 04-15 Sun (106 = 04-22 Sun) easter: 04-22 Sun (113 = 05-01 Sun) ifc easter: 04-15 Sun (106 = 04-22 Sun)
1985: full moon: 04-05 Fri (095 = 04-11 Wed) easter: 04-07 Sun (097 = 04-13 Fri) ifc easter: 04-09 Tue (099 = 04-15 Sun)
1986: full moon: 03-26 Wed (085 = 04-01 Sun) easter: 03-30 Sun (089 = 04-05 Thu) ifc easter: 03-26 Wed (085 = 04-01 Sun)
1987: full moon: 04-14 Tue (104 = 04-20 Fri) easter: 04-19 Sun (109 = 04-25 Wed) ifc easter: 04-16 Thu (106 = 04-22 Sun)
1988: full moon: 04-02 Sat (093 = 04-09 Mon) easter: 04-03 Sun (094 = 04-10 Tue) ifc easter: 04-08 Fri (099 = 04-15 Sun)
1989: full moon: 03-22 Wed (081 = 03-25 Wed) easter: 03-26 Sun (085 = 04-01 Sun) ifc easter: 03-26 Sun (085 = 04-01 Sun)
1990: full moon: 04-10 Tue (100 = 04-16 Mon) easter: 04-15 Sun (105 = 04-21 Sat) ifc easter: 04-16 Mon (106 = 04-22 Sun)
1991: full moon: 03-30 Sat (089 = 04-05 Thu) easter: 03-31 Sun (090 = 04-06 Fri) ifc easter: 04-02 Tue (092 = 04-08 Sun)
1992: full moon: 04-17 Fri (108 = 04-24 Tue) easter: 04-19 Sun (110 = 04-26 Thu) ifc easter: 04-22 Wed (113 = 05-01 Sun)
1993: full moon: 04-06 Tue (096 = 04-12 Thu) easter: 04-11 Sun (101 = 04-17 Tue) ifc easter: 04-09 Fri (099 = 04-15 Sun)
1994: full moon: 03-27 Sun (086 = 04-02 Mon) easter: 04-03 Sun (093 = 04-09 Mon) ifc easter: 04-02 Sat (092 = 04-08 Sun)
1995: full moon: 04-15 Sat (105 = 04-21 Sat) easter: 04-16 Sun (106 = 04-22 Sun) ifc easter: 04-16 Sun (106 = 04-22 Sun)
1996: full moon: 04-04 Thu (095 = 04-11 Wed) easter: 04-07 Sun (098 = 04-14 Sat) ifc easter: 04-08 Mon (099 = 04-15 Sun)
1997: full moon: 03-24 Mon (083 = 03-27 Fri) easter: 03-30 Sun (089 = 04-05 Thu) ifc easter: 03-26 Wed (085 = 04-01 Sun)
1998: full moon: 04-11 Sat (101 = 04-17 Tue) easter: 04-12 Sun (102 = 04-18 Wed) ifc easter: 04-16 Thu (106 = 04-22 Sun)
1999: full moon: 03-31 Wed (090 = 04-06 Fri) easter: 04-04 Sun (094 = 04-10 Tue) ifc easter: 04-02 Fri (092 = 04-08 Sun)
2000: full moon: 04-18 Tue (109 = 04-25 Wed) easter: 04-23 Sun (114 = 05-02 Mon) ifc easter: 04-22 Sat (113 = 05-01 Sun)
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