jday man page

jday, j2d — astronomical julian date conversion utilities

Synopsis

jday

jday [-d [-]year-mm-dd hh:mm:ss]

jday [--version]

jday [--h[elp]]

j2d <julian decimal date>

j2d [--version]

j2d [--h[elp]]

Description

jday and j2d are command line utilities to convert calendar dates to astronomical julian dates, and julian dates to calendar dates. There is a corresponding library libjday.a which can be used for the same functionality within applications.

Options

jday accepts the following options:

none at all
jday will simply print out the julian date based on the date and time found on the system.
[year [month [day [hour [minute [second]]]]]]
Always in that order, to override that value found on the system.
-d [-]year-mm-dd hh:mm:ss
Specify a year in the same format as that printed out by j2d
j2d accepts the following options:
<julian decimal date>
This is the only, and required argument to j2d
both commands accept the following options:
--version
Display the version of the programs.
--h[elp]
Display a command help message

Examples

$ jday 1970 1 1 12 0 0
2440588.000000
$ jday 0 1 1 12 0 0
1721058.000000
$ jday -4712 1 1 12 0 0
0.000000
$ jday -d -4712-01-01 12:00:00
0.000000
$ j2d 0.0
-4712-01-01 12:00:00
$ j2d 1721058.0
0-01-01 12:00:00
$ j2d 2440588.0
1970-01-01 12:00:00

See Also

Time Standard: http://tycho.usno.navy.mil
Systems of time: http://tycho.usno.navy.mil/systime.html

Info

10 October 2005 Version 2.4