Julian date


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Related to Julian date: Julian calendar, Gregorian date
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Julian Date

Julian date

(JD) The number of days that have elapsed since noon GMT on Jan. 1 4713 bc – the Julian day number – plus the decimal fraction of the day that has elapsed since the preceding noon. The consecutive numbering of days makes the system independent of the length of month or year and the JD is thus used to calculate the frequency of occurrence or the periodicity of phenomena over long periods. The system was devised in 1582 by the French scholar Joseph Scaliger. A specific Julian date can be determined from astronomical tables of Julian day numbers: thus since March 1 1980, noon GMT, is tabulated as day number 244 4300 then March 17 1980, 6 p.m. GMT, is JD 244 4316.25 (see table). The modified Julian date (MJD) is found by subtracting 240 0000.5 from the Julian date.

Julian date

[′jül·yən ¦dāt]
(astronomy)
The sum of the Julian day number and the fraction of a day elapsed since the previous noon.

Julian date

A calendar notation in which the date is represented by one number. For example, the Julian date for December 11, 1942 is 2430705; while December 12, 1942 is 2430706. The Julian date is widely used with computers because it requires less programming to compare dates that are single integers. Julian numbers are also used within a single year; for example, February 1 is Julian 32.

Developed in the 16th century by Joseph Scaliger, the numbers were based on a 7,980-year cycle that began on January 1, 4713 BC and ends January 22, 3268. Contrast with "Gregorian date," which is the common calendar notation of month, day and year.
References in periodicals archive ?
The morph type (long, mid, or short), and Julian dates of initiation and completion of flowering were recorded for all individuals within the population.
Detection increased with playback of barn owl vocalizations, increasing Julian date, and lower background noise (Table 2).
The inflection point is the Julian date at which the concavity of the model changes and capture rate begins to slow.
The Julian date can be stored as a 4-byte integer, no more bytes than required by the format MM/DD/YY, and can in theory store a Julian date, if the integers are unsigned, up to 4294967295.
The survival function for the Kelowna population in the third generation of 1993 has an intermediate peak in survival probability near Julian date 270, and very low survival at the highest TF dates (Fig.
It was subject to the effects of release sites (F = 2.0, df = 12, P = 0.03) and the interaction between release site and Julian date (F = 2.1, df = 12, P = 0.03).
Astronomical programs are fairly immune to millennium problems because they are designed to operate well into the past and future and perform calculations based on Julian Date, the number of days since January 1, 4713 B.C.
Similarly, pages by Ontario's Hamilton Amateur Astronomers (http://www.science.mcmaster.ca/HAA/) will calculate Julian date and astrophotography exposure times.
Julian dates can be found from the numbers just after the month names on the chart's left.
Calendar days of the arrival and departure of flocks were converted into Julian dates (1 for 1st July) with correction for leap- years.
In cooperation with the FDA, Cal-Maine immediately notified its customers and recalled specific Julian dates of shell eggs because they have the potential to be contaminated with SE.
Such as "C" equals change Julian dates by two days forward and once the pro-word "Corona" is called over the FM all know what to do.