[Numpy-discussion] Time Zones and datetime64

Riccardo De Maria riccardodemaria@gmail....
Sat Apr 13 02:42:16 CDT 2013


Colin J. Williams <cjwilliams43 <at> gmail.com> writes:

> well, I don't see any timezone support in there at all. It appears the
> use UTC, though I"m not entierly sure from the docs what now() would
> return.
> 
> So I think it's pretty much like my "use UTC" proposal.

I think so. There is no support for leap second either.
 
>     It's not clear whether the Julian day is an integer or contains
>       a fractional part.
>       Colin W.

In SQLite the internal representation is Julian day * 86400 * 1000.

In astronomy the modified julian day is apparenly often used:
CCIR RECOMMENDATION 457-1, USE OF THE MODIFIED JULIAN DATE BY THE STANDARD
FREQUENCY AND TIME-SIGNAL SERVICES.

There is python library with classes that support several 
time coordinate systems (TAI, UTC, ISO, JD, MJD, UNX, RDT, CDF, DOY, eDOY)

http://spacepy.lanl.gov/doc/autosummary/spacepy.time.Ticktock.html

I also found those page useful for a quick recap.

http://tycho.usno.navy.mil/mjd.html
http://tycho.usno.navy.mil/systime.html





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