# why the 0.5 in the Unix Epoch (for UnixToDateTime function)

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## why the 0.5 in the Unix Epoch (for UnixToDateTime function)

 I just noticed that the definition of the constants have 0.5 in it. Why? from dateh.inc const     JulianEpoch = TDateTime(-2415018.5);     UnixEpoch = JulianEpoch + TDateTime(2440587.5); Dennis _______________________________________________ fpc-pascal maillist  -  [hidden email] http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
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## Re: why the 0.5 in the Unix Epoch (for UnixToDateTime function)

 Hi,   wiki https://en.wikipedia.org/wiki/Julian_day says that "... Julian day number 0 assigned to the day starting at noon on January 1, 4713 BC, ..." The noon means 0,5.   V. ______________________________________________________________ > Od: Dennis <[hidden email]> > Komu: FPC-Pascal users discussions <[hidden email]> > Datum: 01.08.2017 13:14 > Předmět: [fpc-pascal] why the 0.5 in the Unix Epoch (for UnixToDateTime function) > I just noticed that the definition of the constants have 0.5 in it. Why? from dateh.inc const    JulianEpoch = TDateTime(-2415018.5);    UnixEpoch = JulianEpoch + TDateTime(2440587.5); Dennis _______________________________________________ fpc-pascal maillist  -  [hidden email] http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal _______________________________________________ fpc-pascal maillist  -  [hidden email] http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
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## Re: why the 0.5 in the Unix Epoch (for UnixToDateTime function)

 In reply to this post by Dennis Hi,   wiki https://en.wikipedia.org/wiki/Julian_day says that "... Julian day number 0 assigned to the day starting at noon on January 1, 4713 BC, ..." The noon means 0,5.   V. ______________________________________________________________ > Od: Dennis <[hidden email]> > Komu: FPC-Pascal users discussions <[hidden email]> > Datum: 01.08.2017 13:14 > Předmět: [fpc-pascal] why the 0.5 in the Unix Epoch (for UnixToDateTime function) > I just noticed that the definition of the constants have 0.5 in it. Why? from dateh.inc const    JulianEpoch = TDateTime(-2415018.5);    UnixEpoch = JulianEpoch + TDateTime(2440587.5); Dennis _______________________________________________ fpc-pascal maillist  -  [hidden email] http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal _______________________________________________ fpc-pascal maillist  -  [hidden email] http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
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## Re: why the 0.5 in the Unix Epoch (for UnixToDateTime function)

 Vojtěch Čihák wrote: > > Hi, > > wiki https://en.wikipedia.org/wiki/Julian_day says that "... Julian > day number 0 assigned to the day starting at noon on January 1, 4713 > BC, ..." > > The noon means 0,5. > Thanks, that is a weird definition though IMHO. Dennis _______________________________________________ fpc-pascal maillist  -  [hidden email] http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
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## Re: why the 0.5 in the Unix Epoch (for UnixToDateTime function)

 On 01/08/17 12:15, Dennis Poon wrote: > Vojtěch Čihák wrote:>> Hi,>> wiki > https://en.wikipedia.org/wiki/Julian_day says that "... Julian > day > number 0 assigned to the day starting at noon on January 1, 4713 > BC, > ...">> The noon means 0,5.>Thanks,that is a weird definition though IMHO. Astronomer's convention. -- Mark Morgan Lloyd markMLl .AT. telemetry.co .DOT. uk [Opinions above are the author's, not those of his employers or colleagues] _______________________________________________ fpc-pascal maillist  -  [hidden email] http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal