![]() Current value is as of 22:32, Friday, Septem( UTC) and may be cached. 0h is 00:00 midnight, 12h is 12:00 noon, UT unless otherwise specified. The date given is a Gregorian calendar date unless otherwise specified. ![]() In the table below, Epoch refers to the point in time used to set the origin (usually zero, but (1) where explicitly indicated) of the alternative convention being discussed in that row. In the following table, times are given in 24-hour notation. A more recent starting point is sometimes used, for instance by dropping the leading digits, in order to fit into limited computer memory with an adequate amount of precision. Variants īecause the starting point or reference epoch is so long ago, numbers in the Julian day can be quite large and cumbersome. Time intervals calculated from differences of Julian Dates specified in non-uniform time scales, such as UTC, may need to be corrected for changes in time scales (e.g. The fraction of the day is found by converting the number of hours, minutes, and seconds after noon into the equivalent decimal fraction. Seidelmann indicates that Julian dates may be used with International Atomic Time (TAI), Terrestrial Time (TT), Barycentric Coordinate Time (TCB), or Coordinated Universal Time (UTC) and that the scale should be indicated when the difference is significant. Historically, Julian dates were recorded relative to Greenwich Mean Time (GMT) (later, Ephemeris Time), but since 1997 the International Astronomical Union has recommended that Julian dates be specified in Terrestrial Time. In contexts where a "Julian date" means simply an ordinal date, calendars of a Gregorian year with formatting for ordinal dates are often called "Julian calendars", but this could also mean that the calendars are of years in the Julian calendar system. This is why the terms "ordinal date" or "day-of-year" are preferred. Other possible meanings of a "Julian date" of "36" include an astronomical Julian Day Number, or the year AD 36 in the Julian calendar, or a duration of 36 astronomical Julian years). Without an astronomical or historical context, a "Julian date" given as "36" most likely means the 36th day of a given Gregorian year, namely February 5. For example, if a given "Julian date" is "October 5, 1582", this means that date in the Julian calendar (which was October 15, 1582, in the Gregorian calendar-the date it was first established). The term Julian date may also refer, outside of astronomy, to the day-of-year number (more properly, the ordinal date) in the Gregorian calendar, especially in computer programming, the military and the food industry, or it may refer to dates in the Julian calendar. 4.6 Julian Period from indiction, Metonic and solar cycles.4.5 Julian or Gregorian calendar from Julian day number.4.4 Finding day of week given Julian day number.4.3 Finding Julian date given Julian day number and time of day.4.2 Converting Julian calendar date to Julian Day Number.4.1 Converting Gregorian calendar date to Julian Day Number.Expressed as a Julian date, this page was loaded at 2459846.438912. Julian dates are expressed as a Julian day number with a decimal fraction added. The Julian date (JD) of any instant is the Julian day number plus the fraction of a day since the preceding noon in Universal Time. For example, the Julian day number for the day starting at 12:00 UT (noon) on January 1, 2000, was 2 451 545. The Julian day number (JDN) is the integer assigned to a whole solar day in the Julian day count starting from noon Universal Time, with Julian day number 0 assigned to the day starting at noon on Monday, January 1, 4713 BC, proleptic Julian calendar (November 24, 4714 BC, in the proleptic Gregorian calendar), a date at which three multi-year cycles started (which are: Indiction, Solar, and Lunar cycles) and which preceded any dates in recorded history. Historians used the period to identify Julian calendar years within which an event occurred when no such year was given in the historical record, or when the year given by previous historians was incorrect. The next Julian Period begins in the year AD 3268. The Julian calendar year 2022 is year 6735 of the current Julian Period. The Julian period is a chronological interval of 7980 years year 1 of the Julian Period was 4713 BC (−4712). The Julian day is the continuous count of days since the beginning of the Julian period, and is used primarily by astronomers, and in software for easily calculating elapsed days between two events (e.g. Not to be confused with Julian year (astronomy).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |