[AstroPy] time conversion between JD and UT

[gonghang.naoc]

You mean jd2 is very small? It can be as large as,say, 0.3.



On Thu, Sep 4, 2014 at 10:54 PM, Tim Jenness <tim.jenness at gmail.com> wrote:

>
>
>
> On Thu, Sep 4, 2014 at 4:59 AM, gonghang.naoc <ghang.naoc at gmail.com>
> wrote:
>
>> Hi all,
>> I am trying astropy.time to do conversion between JD and UT.
>> It is easier to convert UT to JD.  It seems JD equals jd1+jd2, right?  I
>> do not know why there are two parts since one value is enough.
>>
>
> There are two values to allow you use high precision. A single double
> precision number can not provide you with nanosecond precision as a JD. If
> you split the JD into two distinct numbers (apportioned in a way that best
> suits your requirements) you can retain accuracy.
>
> --
> Tim Jenness
>
>
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