Robert Creager

NAME

Astro::Time::HJD - Perl extension for calculating heliocentric julian date adjustment.

SYNOPSIS

 use Astro::Time::HJD qw( correction );
 ($correction, $jd, $hjd ) = correction( $jd, $ra, $dec );
 $correction = correction( $jd, $ra, $dec );

DESCRIPTION

Given an observation date, right ascention and declination, calculates the correction to be added to the julian date of the observation to adjust it's observation time to a heliocentric julian date.

USAGE

correction
(SCALAR, SCALAR, SCALAR) = correction( SCALAR, SCALAR, SCALAR )
SCALAR = correction( SCALAR, SCALAR, SCALAR )

The first form returns the heliocentric correction (in julian days), the original julian date and the adjusted julian date for the given observation time and RA/DEC location. The second form returns just the heliocentric correction. The correction should be added from the julian date of the observation. The first argument to the function is the date of the observation. The date can be either a julian date or a zero padded date time string of the form 'YYYY-MM-DDTHH:MM:SS'. The second and third arguments are the RA and DEC, respectively, given in decimal degrees.

ACCURACY

The algorithms implemented have a stated accuracy of "better than .1 seconds from 1900 through 2050" per Patrick Wallace. Write me in 2049 and I'll see about updating this.

AUTHOR

Robert Creager <Astro-HJD@LogicalChaos.org>

Patrick Wallace, personal communication Michael Koppelman, personal communication