I ended up using Perl's DateTime::Event::Sunrise (formerly DateTime::Astro::Sunrise), because it tends to be easier for me to deploy a module from CPAN than to compile C programs.
Sample usage:
use DateTime; use DateTime::Event::Sunrise; $latitude = "+48.857"; $longitude = "+2.351"; $sr = DateTime::Astro::Sunrise->new($longitude, $latitude, 0, 3); $date = DateTime->now; $date->set_time_zone("local"); ($rise, $set) = $sr->sunrise($date); $rise->set_time_zone("local"); $set->set_time_zone("local"); print $rise, " to ", $set, "\n";
My complete sunrise script:
#!/usr/bin/env perl $^W = 1; use strict; use Getopt::Long; use DateTime; use DateTime::Event::Sunrise; my $cvsid = '$Id$'; my %altitudes = ( center => 0, # center of sun's disk touches a mathematical horizon limb => -0.25, # sun's upper limb touches a mathematical horizon rcenter => -0.583, # center of sun's disk looks like it touches the horizon rlimb => -0.833, # sun's upper limb looks like it touches the horizon civil => -6, # reading outside requires artificial illumination nautical => -12, # navigation using a sea horizon no longer possible amateur => -15, # the sky is dark enough for most astronomical observations astronomical => -18, # the sky is completely dark ); sub help_and_exit { print "Usage: $0 [OPTION]...", <<'EOF'; Show the time of sunrise and sunset at the given location. -x, --longitude=NUM longitude (degrees, >0 for east or xxxE or xxxW) -y, --latitude=NUM latitude (degrees, >0 for north or xxxN or xxxS) -a, --altitude=NUM sun altitude (pass 'help' to list symbolic names) -i, --iter=N number of iterations (rarely needed) -f, --format=FORMAT time display format -d, --date=DATE day to consider (default: today) --help display this help and exit --version output version information and exit EOF exit; } sub version_and_exit { print "sunrise $cvsid\n"; exit; } sub validate_xy { my ($s, $name, $neg, $pos) = @_; die "No $name specified!" unless defined $s; $s =~ tr/\t //; my $negative = ($s =~ s/^([-+])// && $1 eq '-'); my $opposite = ($s =~ s/(\Q$pos\E|\Q$neg\E)$//i && lc($1) eq lc($neg)); my $sign = ($negative ^ $opposite ? '-' : '+'); die "Badly formed number in $name!\n" unless $s =~ /^(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)$/; $s .= ".0" unless $s =~ /\./; return "$sign$s"; } sub sun_rise_set { my ($long, $lat, $alt, $iter, $dt) = @_; my $sr = DateTime::Event::Sunrise->new($long, $lat, $alt, $iter); my ($rise, $set) = $sr->sunrise($dt); my $tz = $dt->time_zone; $rise->set_time_zone($tz); $set->set_time_zone($tz); return $rise, $set; } sub main { ## Default values my ($long, $lat) = (undef, undef); my $alt = $altitudes{rlimb}; my $iter = 3; my $locale = "en_IE"; my $time_format = "%c %Z"; my $dt = undef; ## Command line parsing GetOptions( "x|longitude=s" => \$long, "y|latitude=s" => \$lat, "a|altitude=s" => \$alt, "i|iter=i" => \$iter, "f|format=s" => \$time_format, "d|date=s" => \$dt, "help" => \&help_and_exit, "version" => \&version_and_exit, ) or die "$0: invalid command line (try --help)\n"; # TODO: options for locale?, timezone if ($alt eq 'help') { foreach my $z (sort {$a->[1] <=> $b->[1]} map {[$_,$altitudes{$_}]} keys %altitudes) { printf "%-19s %g\n", @$z; } exit; } $long = validate_xy($long, "longitude", "w", "e"); $lat = validate_xy($lat, "latitude", "s", "n"); $alt = $altitudes{lc($alt)} if exists $altitudes{lc($alt)}; die "Badly formed altitude (try --altitude=help)!" unless $alt =~ /^[-+]?(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)$/; if (defined $dt) { require Date::Manip; $dt = DateTime->new( Date::Manip::UnixDate( Date::Manip::ParseDateString($dt), qw[year %Y month %m day %d], qw[hour %H minute %M second %S], qw[time_zone %z])); } else { $dt = DateTime->now; $dt->set_time_zone("local"); } ## Compute and display my ($rise, $set) = sun_rise_set($long, $lat, $alt, $iter, $dt); $rise->set_locale($locale); $set->set_locale($locale); print $rise->strftime($time_format), "\n"; print $set->strftime($time_format), "\n"; } main(@ARGV);
