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JDAY(1)                               2.4                              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 (C)  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.

       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
               CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
               INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
               MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
               DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
               LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
               EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
               TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
               DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
               ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
               LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
               IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
               THE POSSIBILITY OF SUCH DAMAGE.

Version                         10 October 2005                        JDAY(1)

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