Explanatory supplement to the Astronomical Almanac' 3rd ed. Chronological dating Geologic time scale International Commission on Stratigraphy. JD stands for Julian Date. Time intervals calculated from differences of Julian Dates specified in non-uniform time scales, such as Coordinated Universal Time UTCmay need to be corrected for changes in time scales e. Outlines of Astronomy London:
Hence, to refer the Christian era to the Julian Period is the same thing as to find out what year of that period it is which, when divided by 28 will leave a remainder 10, divided by 19 will leave a remainder 2, and divided by 15 will leave a remainder 4.
Thus, the day of the week can be obtained from the remainder of the division of the Julian date by 7. Noerdlinger, P. Nevertheless, he double-dated most nighttime observations with both Egyptian days beginning at sunrise and Babylonian days beginning at sunset. The second formula is a bit trickier. In point of fact, finding the year is a very straightforward arithmetical procedure. From Wikipedia, the free encyclopedia. Computer processing of dates outside the twentieth century.