Astro::Time - Time based astronomical routines
use Astro::Time; $dayno = cal2dayno($day, $month, $year); print "It's a leap year!\n" if (leap($year)); $lmst = mjd2lst($mjd, $longitude, $dUT1); $turns = str2turn($string, 'H'); $str = turn2str($turn, 'D', $sig);
Astro::Time contains an assorted set Perl routines for time based conversions, such as conversion between calendar dates and Modified Julian day and conversion of UT to local sidereal time. Include are routines for conversion between numerical and string representation of angles.
Chris Phillips Chris.Phillips@csiro.au
$str = turn2str($turn, $mode, $sig); $str = turn2str($turn, $mode, $sig, $strsep); Convert fraction of a turn into string representation $turn Angle in turns $mode Mode of string to convert to: 'H' for hours 'D' for degrees $sig number of significant figures $strsep String separator (override for default $Astro::Time::StrSep) Note: The behavior can be modified by the following two variables: $Astro::Time::StrZero Minimum number of leading digits (zero padded if needed) $Astro::Time::StrSep (Overridden by optional fourth argument) Deliminator used in string (Default ':') This may also equal one of a number of special values: 'HMS' 12H45M12.3S or 170D34M56.2S 'hms' 12h45m12.3s or 170d34m56.2s 'deg' 170d34'56.2"
$str=deg2str($deg, $mode, $sig); Convert degrees into string representation $deg angle in degrees $mode mode of string to convert to: 'H' for hours 'D' for degrees $sig number of significant figures See note for turn2str
$str=rad2str($rad, $mode, $sig); Convert radians into string representation $rad angle in radians $mode mode of string to convert to: 'H' for hours 'D' for degrees $sig is number of significant figures See note for turn2str
$turns = str2turn($string,$mode); Convert angle from string representation into fraction of a turn $string a : or space delimited angle $mode type of angle 'H' if $string is in hours,min,sec 'D' if $string is in deg,arcmin,arcsec The format of $string can be fairly flexible e.g.: 12.2 12:34 12:34:45.1 -23 34 12.3 -34 34.3 Note: You cannot mix spaces and :
$degrees=str2deg($string,$mode); Convert angle from string representation into degrees $string a : or space delimited angle $mode 'H' if $string is in hours,min,sec 'D' if $string is in deg,arcmin,arcsec See note for str2turn
$radians=str2rad($string,$mode); Convert angle from string representation into radians $string a : or space delimited angle $mode 'H' if $string is in hours,min,sec 'D' if $string is in deg,arcmin,arcsec See note for str2turn
($time) = hms2time($hour, $minute, $second); ($time) = hms2time($hour, $minute, $second, $mode); Returns the day fraction given hours minutes and seconds (or degrees) $time Day fraction $hour Hours $minutes Minutes $second Seconds $mode 'H' or 'D' to interpret as hours or degrees (default hours)
($sign, $hour, $minute, $second) = time2hms($time, $mode, $sig); Returns hours (or degrees), minutes and seconds given the day fraction $sign Sign of angle ('+' or '-') $hour Hours $minutes Minutes $second Seconds $time Day fraction $mode Return degrees or Hours? 'H' for hours 'D' for degrees $sig Number of significant digits for $second
$rad=deg2rad($deg); Convert degrees to radians
$deg=rad2deg($rad); Convert radians to degrees
$rad=turn2rad($turn); Convert turns to radians
$turn=rad2turn($rad); Convert radians to turns
$deg=turn2deg($turn); Convert turns to radians
$turn=deg2turn($deg); Convert degrees to turns
$dayno = cal2dayno($day, $month, $year); Returns the day number corresponding to $day of $month in $year.
($day, $month) = dayno2cal($dayno, $year); Return the $day and $month corresponding to $dayno of $year.
$isleapyear = leap($year); Returns true if $year is a leap year. $year year in full
($dayno, $year) = yesterday($dayno, $year); ($day, $month, $year) = yesterday($day, $month, $year); Winds back the day number by one, taking account of year wraps. $dayno Day number of year $year Year $month Month $day Day of month
($dayno, $year) = tomorrow($dayno, $year); ($day, $month, $year) = tomorrow($day, $month, $year); Advances the day number by one, taking account of year wraps. $dayno Day number of year $year Year $month Month $day Day of month
($day, $month, $year, $ut) = mjd2cal($mjd); Converts a modified Julian day number into calendar date (universal time). (based on the slalib routine sla_djcl). $mjd Modified Julian day (JD-2400000.5) $day Day of the month. $month Month of the year. $year Year $ut UT day fraction
$mjd = cal2mjd($day, $month, $year, $ut); Converts a calendar date (universal time) into modified Julian day number. $day Day of the month. $month Month of the year. $year Year $ut UT dayfraction $mjd Modified Julian day (JD-2400000.5)
($dayno, $year, $ut) = mjd2dayno($mjd); Converts a modified Julian day number into year and dayno (universal time). $mjd Modified Julian day (JD-2400000.5) $year Year $dayno Dayno of year
$mjd = dayno2mjd($dayno, $year, $ut); Converts a dayno and year to modified Julian day $mjd Modified Julian day (JD-2400000.5) $year Year $dayno Dayno of year
$mjd = now2mjd()
$mjd = jd2mjd($jd); Converts a Julian day to Modified Julian day $jd Julian day $mjd Modified Julian day
$jd = mjd2jd($mjd); Converts a Modified Julian day to Julian day $mjd Modified Julian day $jd Julian day
$str = mjd2time($mjd); $str = mjd2time($mjd, $np); Converts a Modified Julian day to a formatted string $mjd Modified Julian day $str Formatted time $np Number of significant digits for fraction of a sec. Default 0
$gst = gst($mjd); $gmst = gst($mjd, $dUT1); $gtst = gst($mjd, $dUT1, $eqenx); Converts a modified Julian day number to Greenwich sidereal time $mjd modified Julian day (JD-2400000.5) $dUT1 difference between UTC and UT1 (UT1 = UTC + dUT1) (seconds) $eqenx Equation of the equinoxes (not yet supported) $gst Greenwich sidereal time (turns) $gmst Greenwich mean sidereal time (turns) $gtst Greenwich true sidereal time (turns)
$lst = mjd2lst($mjd, $longitude); $lmst = mjd2lst($mjd, $longitude, $dUT1); $ltst = mjd2lst($mjd, $longitude, $dUT1, $eqenx); Converts a modified Julian day number into local sidereal time (lst), local mean sidereal time (lmst) or local true sidereal time (ltst). Unless high precisions is required dUT1 can be omitted (it will always be in the range -0.5 to 0.5 seconds). $mjd Modified Julian day (JD-2400000.5) $longitude Longitude for which the LST is required (turns) $dUT1 Difference between UTC and UT1 (UT1 = UTC + dUT1)(seconds) $eqenx Equation of the equinoxes (not yet supported) $lst Local sidereal time (turns) $lmst Local mean sidereal time (turns) $ltst Local true sidereal time (turns)
$lst = cal2lst($day, $month, $year, $ut, $longitude); $lmst = cal2lst($day, $month, $year, $ut, $longitude, $dUT1); $ltst = cal2lst($day, $month, $year, $ut, $longitude, $dUT1, $eqenx); Wrapper to mjd2lst using calendar date rather than mjd
$lst = dayno2lst($dayno, $year, $ut, $longitude); $lmst = dayno2lst($dayno, $year, $ut, $longitude, $dUT1); $ltst = dayno2lst($dayno, $year, $ut, $longitude, $dUT1, $eqenx); Wrapper to mjd2lst using calendar date rather than mjd
($lst_rise, $lst_set) = rise($ra, $dec, $obslat, $el_limit); Return the lst rise and set time of the given source $lst_rise, $lst_set Rise and set time (turns) $ra, $dec RA and Dec of source (turns) $obslat Latitude of observatory (turns) $el_limit Elevation limit of observatory (turns, 0 horizontal) Returns 'Circumpolar' if source circumpolar Returns undef if source never rises Uses the formula: cos $z_limit = sin $obslat * sin $dec + cos $obslat * cos $dec * cos $HA where: $z_limit is the zenith angle limit corresponding to $el_limit $HA is the Hour Angle of the source NOTE: For maximum accuracy source coordinated should be precessed to the current date.
$mjd = lst2mjd($lmst, $dayno, $year, $longitude); $mjd = lst2mjd($lmst, $dayno, $year, $longitude, $dUT1); This routine calculates the modified Julian day number corresponding to the local mean sidereal time $lmst at $longitude, on a given UT day number ($dayno). Unless high precision is required dUT1 can be omitted. The required inputs are : $lmst - The local mean sidereal time (turns) $dayno - The UT day of year for which to do the conversion $year - The year for which to do the conversion $longitude - The longitude of the observatory (turns) $dUT1 - Difference between UTC and UT1 (UT1 = UTC + dUT1) (seconds) $mjd The modified Julian day corresponding to $lmst on $dayno
1 POD Error
The following errors were encountered while parsing the POD:
'=item' outside of any '=over'
=over without closing =back
To install Astro::Time, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Astro::Time
CPAN shell
perl -MCPAN -e shell install Astro::Time
For more information on module installation, please visit the detailed CPAN module installation guide.