[Python-ideas] High Precision datetime

Alexander Belopolsky alexander.belopolsky at gmail.com
Thu May 17 19:41:19 EDT 2018

On Thu, May 17, 2018 at 7:12 PM Wes Turner <wes.turner at gmail.com> wrote:

> AstroPy solves for leap seconds [1][2] according to the IAU ERFA (SOFA)
> library [3] and the IERS-B and IERS-A tables [4]. IERS-B tables ship with
> AstroPy. The latest IERS-A tables ("from 1973 though one year into the
> future") auto-download on first use [5].

I've just tried it.  Unfortunately, it does not seem to be compatible with
PEP 495 datetime yet:

>>> t = astropy.time.Time('2016-12-31T23:59:60')
>>> t.to_datetime()
Traceback (most recent call last):
ValueError: Time (array(2016, dtype=int32), array(12, dtype=int32),
array(31, dtype=int32), array(23, dtype=int32), array(59, dtype=int32),
array(60, dtype=int32), array(0, dtype=int32)) is within a leap second but
datetime does not support leap seconds

Maybe someone can propose a feature for astropy to return
datetime(2016,12,31,23,59,59,fold=1) in this case.

> [1] http://docs.astropy.org/en/stable/time/#time-scales-for-time-deltas
> [2] http://docs.astropy.org/en/stable/time/#writing-a-custom-format
> [3] "Leap second day utc2tai interpolation"
> https://github.com/astropy/astropy/issues/5369
> [4] https://github.com/astropy/astropy/pull/4436
> [5] http://docs.astropy.org/en/stable/utils/iers.html
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