jday [-d [-]year-mm-dd hh:mm:ss]
j2d <julian decimal date>
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.
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:
Display the version of the programs.
Display a command help message
$ jday 1970 1 1 12 0 0
$ jday 0 1 1 12 0 0
$ jday -4712 1 1 12 0 0
$ jday -d -4712-01-01 12:00:00
$ j2d 0.0
$ j2d 1721058.0
$ j2d 2440588.0
Time Standard: http://tycho.usno.navy.mil
Systems of time: http://tycho.usno.navy.mil/systime.html
Copyright © 1986-2005, Hiram Clawson
- jday at hiram.ws
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without modification, are permitted provided that the following conditions are met:
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