Julian century

A Julian century is defined as the duration of 36,525 days, i.e. 100 Julian years of 365.25 days each.

The day was understood to mean:

• earlier a mean sunny day
• since 1960 one day to 86,400  ephemeris seconds
• Today is a day of 86,400 seconds of the International System  of Units .

Ten Julian centuries make up a Julian millennium .

application

In astronomical calculations, the number of Julian centuries since a standard epoch is often required for a specific date . Usually the symbol T is used for this  . The value results as:

${\displaystyle T={\frac {JD_{\text{Datum}}-JD_{\text{Standard-Epoche}}}{36525}}}$

JD stands for the respective Julian date . For a date earlier than the standard epoch, T is negative.

Examples: Julian centuries on December 31, 1899 00:00  Universal time since  B1950.0 :

${\displaystyle T={\frac {2415019{,}5-2433282{,}423}{36525}}=-0{,}500012}$

Julian centuries on January 1, 2010 00:00  DD since  J2000.0 :

${\displaystyle T={\frac {2455197{,}5-2451545{,}0}{36525}}=0{,}100000}$.

Accordingly, the number of Julian millennia since a standard epoch results as:

${\displaystyle T={\frac {JD_{\text{Datum}}-JD_{\text{Standard-Epoche}}}{365250}}}$.