JDAY(1)

NAME
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

COPYRIGHT
Copyright © 1986-2005, Hiram Clawson

jday at hiram.ws

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

    Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

    Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

    Neither name of The Museum of Hiram nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

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