ap">N<sub>-201</sub></span>. So we need to calculate A(-201) for both epoch A and epoch B.</p>
    
<p>Let's do the calculation for epoch A first. From Table 4, we find <span class="nowrap">JD(M<sub>0</sub>)</span> = 1589523.5, <span class="nowrap">y<sub>z</sub></span> = -225 and <span class="nowrap">&Delta;A</span> = 1670. Hence we have<br />
c = floor((-201 + 225)/19) = 1<br />
k = -201 + 225 - 19 = 5<br />
J(5) = 1, but epoch A is not valid after month 1. It is epoch B that determines if <span class="now