How To Calculate the Julian Day
These are the steps:
let a = (10000.0 * year) + (100.0 * (month)) + day;
note: a should be > -47120101
If month <= 2 then add 12 to month to become 13 or 14 and substract 1 from year
let b1 = Floor(year / 400)
let b2 = Floor(year / 100)
let b3 = Floor(year / 4)
let a2 = Floor(30.6001 * month+ 1))
let b = b1 – b2 + b3;
make timezone(tz-days) in day unit by dividing on 24
tz-days= timezone/ 24;
also make local time in day unit. for example 3 pm is 15/24. and 3:30 am is 3.5/24 and so on
a = (365.0 * year) + 1720996.5;
Julian day = a + b + a2 + day – timezone+ local time
Here you can get he value for anytime:
Julian Day
You don’t know what is julian Day?
Read more here from wikipedia.
