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

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

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.

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.

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.

Robert Creager <Astro-HJD@LogicalChaos.org>

Patrick Wallace, personal communication Michael Koppelman, personal communication