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Julian day

Index Julian day

Julian day is the continuous count of days since the beginning of the Julian Period and is used primarily by astronomers. [1]

84 relations: Aloysius Lilius, Ancient Egypt, Anno Domini, Astronomer, Astronomical day, Astronomical year numbering, Astronomy, Babylonia, Barycentric Julian Date, Calendar, Chronology, CNES, Common Era, Consultative Committee for Space Data Systems, Coordinated Universal Time, Decimal time, Dennis McCarthy (scientist), Division (mathematics), Dual dating, Dublin, Earth, Edward Charles Pickering, Edward Reingold, Ephemeris, Ephemeris time, Epoch (astronomy), Epoch (reference date), Era, Ernest William Brown, Go (programming language), Goddard Space Flight Center, Gregorian calendar, Harvard College Observatory, Heliocentric Julian Day, History, HM Nautical Almanac Office, IBM, IBM 704, Indiction, International Astronomical Union, International Meridian Conference, Jean Meeus, John Herschel, Joseph Justus Scaliger, Julian calendar, Julian year (astronomy), Julius Caesar, Julius Caesar Scaliger, Leap second, Least common multiple, ..., Lilian date, Metonic cycle, Modular arithmetic, Nachum Dershowitz, NASA, New moon, Newcomb's Tables of the Sun, Ordinal date, Pierre-Simon Laplace, Prime meridian, Proleptic Gregorian calendar, Proleptic Julian calendar, Ptolemy, Python (programming language), Rata Die, Republic of Ireland, Rexx, Smithsonian Astrophysical Observatory, SOFA (astronomy), Solar cycle (calendar), Sputnik 1, Sun, Terrestrial Time, Time, Time standard, United States Department of Agriculture, Universal Time, Unix time, Variable star, Water clock, Week, Zeller's congruence, .NET strategy, 5th millennium BC. Expand index (34 more) »

Aloysius Lilius

Aloysius Lilius (c. 1510 – 1576), also variously referred to as Luigi Lilio, Luigi Giglio, was an Italian doctor, astronomer, philosopher and chronologist, and also the "primary author" who provided the proposal that (after modifications) became the basis of the Gregorian Calendar reform of 1582.

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Ancient Egypt

Ancient Egypt was a civilization of ancient Northeastern Africa, concentrated along the lower reaches of the Nile River - geographically Lower Egypt and Upper Egypt, in the place that is now occupied by the countries of Egypt and Sudan.

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Anno Domini

The terms anno Domini (AD) and before Christ (BC) are used to label or number years in the Julian and Gregorian calendars.

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An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside the scope of Earth.

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Astronomical day

An astronomical day refers to a length of day of exactly or nearly 24 hours beginning at noon instead of at midnight.

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Astronomical year numbering

Astronomical year numbering is based on AD/CE year numbering, but follows normal decimal integer numbering more strictly.

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Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.

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Babylonia was an ancient Akkadian-speaking state and cultural area based in central-southern Mesopotamia (present-day Iraq).

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Barycentric Julian Date

The Barycentric Julian Date (BJD) is the Julian Date (JD) corrected for differences in the Earth's position with respect to the barycentre of the Solar System.

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A calendar is a system of organizing days for social, religious, commercial or administrative purposes.

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Chronology (from Latin chronologia, from Ancient Greek χρόνος, chrónos, "time"; and -λογία, -logia) is the science of arranging events in their order of occurrence in time.

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The Centre national d'études spatiales (CNES) (English: National Centre for Space Studies) is the French government space agency (administratively, a "public administration with industrial and commercial purpose").

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Common Era

Common Era or Current Era (CE) is one of the notation systems for the world's most widely used calendar era – an alternative to the Dionysian AD and BC system.

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Consultative Committee for Space Data Systems

The Consultative Committee for Space Data Systems (CCSDS) was founded in 1982 for governmental and quasi-governmental space agencies to discuss and develop standards for space data and information systems.

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Coordinated Universal Time

No description.

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Decimal time

Decimal time is the representation of the time of day using units which are decimally related.

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Dennis McCarthy (scientist)


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Division (mathematics)

Division is one of the four basic operations of arithmetic, the others being addition, subtraction, and multiplication.

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Dual dating

Dual dating is the practice, in historical materials, to indicate some dates with what appears to be duplicate, or excessive digits, sometimes separated by a hyphen or a slash.

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Dublin is the capital of and largest city in Ireland.

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Earth is the third planet from the Sun and the only astronomical object known to harbor life.

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Edward Charles Pickering

Prof Edward Charles Pickering FRS(For) HFRSE (July 19, 1846 – February 3, 1919) was an American astronomer and physicist and the older brother to William Henry Pickering.

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Edward Reingold

Edward M. Reingold (born 1945) is a computer scientist active in the fields of algorithms, data structures, graph drawing, and calendrical calculations.

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In astronomy and celestial navigation, an ephemeris (plural: ephemerides) gives the positions of naturally occurring astronomical objects as well as artificial satellites in the sky at a given time or times.

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Ephemeris time

The term ephemeris time (often abbreviated ET) can in principle refer to time in connection with any astronomical ephemeris.

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Epoch (astronomy)

In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.

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Epoch (reference date)

In the fields of chronology and periodization, an epoch is an instant in time chosen as the origin of a particular era.

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An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth.

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Ernest William Brown

Ernest William Brown FRS (29 November 1866 – 22 July 1938) was an English mathematician and astronomer, who spent the majority of his career working in the United States and became a naturalised American citizen in 1923.

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Go (programming language)

Go (often referred to as Golang) is a programming language created at Google in 2009 by Robert Griesemer, Rob Pike, and Ken Thompson.

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Goddard Space Flight Center

The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States.

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Gregorian calendar

The Gregorian calendar is the most widely used civil calendar in the world.

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Harvard College Observatory

The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy.

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Heliocentric Julian Day

The Heliocentric Julian Date (HJD) is the Julian Date (JD) corrected for differences in the Earth's position with respect to the Sun.

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History (from Greek ἱστορία, historia, meaning "inquiry, knowledge acquired by investigation") is the study of the past as it is described in written documents.

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HM Nautical Almanac Office

Her Majesty's Nautical Almanac Office (HMNAO), now part of the United Kingdom Hydrographic Office, was established in 1832 on the site of the Royal Greenwich Observatory (RGO), where The Nautical Almanac had been published since 1767.

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The International Business Machines Corporation (IBM) is an American multinational technology company headquartered in Armonk, New York, United States, with operations in over 170 countries.

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IBM 704

The IBM 704, introduced by IBM in 1954, is the first mass-produced computer with floating-point arithmetic hardware.

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An indiction is any of the years in a 15-year cycle used to date medieval documents throughout Europe, both East and West.

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International Astronomical Union

The International Astronomical Union (IAU; Union astronomique internationale, UAI) is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy.

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International Meridian Conference

The International Meridian Conference was a conference held in October 1884 in Washington, D.C., in the United States, to determine a prime meridian for international use.

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Jean Meeus

Jean Meeus (born 12 December 1928) is a Belgian meteorologist and amateur astronomer specializing in celestial mechanics, spherical and mathematical astronomy.

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John Herschel

Sir John Frederick William Herschel, 1st Baronet (7 March 1792 – 11 May 1871) was an English polymath, mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint, and did botanical work.

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Joseph Justus Scaliger

Joseph Justus Scaliger (5 August 1540 – 21 January 1609) was a French religious leader and scholar, known for expanding the notion of classical history from Greek and ancient Roman history to include Persian, Babylonian, Jewish and ancient Egyptian history.

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Julian calendar

The Julian calendar, proposed by Julius Caesar in 46 BC (708 AUC), was a reform of the Roman calendar.

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Julian year (astronomy)

In astronomy, a Julian year (symbol: a) is a unit of measurement of time defined as exactly 365.25 days of SI seconds each.

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Julius Caesar

Gaius Julius Caesar (12 or 13 July 100 BC – 15 March 44 BC), known by his cognomen Julius Caesar, was a Roman politician and military general who played a critical role in the events that led to the demise of the Roman Republic and the rise of the Roman Empire.

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Julius Caesar Scaliger

Julius Caesar Scaliger (April 23, 1484 – October 21, 1558), or Giulio Cesare della Scala, was an Italian scholar and physician, who spent a major part of his career in France.

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Leap second

A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time as realized by UT1.

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Least common multiple

In arithmetic and number theory, the least common multiple, lowest common multiple, or smallest common multiple of two integers a and b, usually denoted by LCM(a, b), is the smallest positive integer that is divisible by both a and b. Since division of integers by zero is undefined, this definition has meaning only if a and b are both different from zero.

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Lilian date

A Lilian date is the number of days since the beginning of the Gregorian Calendar on October 15, 1582, regarded as Lilian date 1.

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Metonic cycle

For astronomy and calendar studies, the Metonic cycle or Enneadecaeteris (from ἐννεακαιδεκαετηρίς, "nineteen years") is a period of very close to 19 years that is nearly a common multiple of the solar year and the synodic (lunar) month.

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Modular arithmetic

In mathematics, modular arithmetic is a system of arithmetic for integers, where numbers "wrap around" upon reaching a certain value—the modulus (plural moduli).

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Nachum Dershowitz

Nachum Dershowitz is an Israeli computer scientist, known e.g. for the Dershowitz–Manna ordering used to prove termination of term rewrite systems.

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The National Aeronautics and Space Administration (NASA) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program, as well as aeronautics and aerospace research.

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New moon

In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude.

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Newcomb's Tables of the Sun

Newcomb's Tables of the Sun is the short title and running head of a work by the American astronomer and mathematician Simon Newcomb entitled "Tables of the Motion of the Earth on its Axis and Around the Sun" on pages 1–169 of "Tables of the Four Inner Planets" (1895), volume VI of the serial publication Astronomical Papers Prepared for the Use of the American Ephemeris and Nautical Almanac.

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Ordinal date

An ordinal date is a calendar date typically consisting of a year and a day of year ranging between 1 and 366 (starting on January 1), though year may sometimes be omitted.

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Pierre-Simon Laplace

Pierre-Simon, marquis de Laplace (23 March 1749 – 5 March 1827) was a French scholar whose work was important to the development of mathematics, statistics, physics and astronomy.

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Prime meridian

A prime meridian is a meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°.

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Proleptic Gregorian calendar

The proleptic Gregorian calendar is produced by extending the Gregorian calendar backward to dates preceding its official introduction in 1582.

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Proleptic Julian calendar

The proleptic Julian calendar is produced by extending the Julian calendar backwards to dates preceding AD 4 when the quadrennial leap year stabilized.

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Claudius Ptolemy (Κλαύδιος Πτολεμαῖος, Klaúdios Ptolemaîos; Claudius Ptolemaeus) was a Greco-Roman mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology.

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Python (programming language)

Python is an interpreted high-level programming language for general-purpose programming.

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Rata Die

Rata Die (R.D.) is a system for assigning numbers to calendar days (optionally with time of day), independent of any calendar, for the purposes of calendrical calculations.

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Republic of Ireland

Ireland (Éire), also known as the Republic of Ireland (Poblacht na hÉireann), is a sovereign state in north-western Europe occupying 26 of 32 counties of the island of Ireland.

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Rexx (Restructured Extended Executor) is an interpreted programming language developed at IBM by Mike Cowlishaw.

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Smithsonian Astrophysical Observatory

The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory (HCO) to form the Harvard–Smithsonian Center for Astrophysics (CfA).

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SOFA (astronomy)

The SOFA (Standards of Fundamental Astronomy) software libraries are a collection of subroutines that implement official International Astronomical Union algorithms for astronomical computations.

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Solar cycle (calendar)

The solar cycle is a 28-year cycle of the Julian calendar with respect to the week.

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Sputnik 1

Sputnik 1 (or; "Satellite-1", or "PS-1", Простейший Спутник-1 or Prosteyshiy Sputnik-1, "Elementary Satellite 1") was the first artificial Earth satellite.

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The Sun is the star at the center of the Solar System.

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Terrestrial Time

Terrestrial Time (TT) is a modern astronomical time standard defined by the International Astronomical Union, primarily for time-measurements of astronomical observations made from the surface of Earth.

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Time is the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future.

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Time standard

A time standard is a specification for measuring time: either the rate at which time passes; or points in time; or both.

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United States Department of Agriculture

The United States Department of Agriculture (USDA), also known as the Agriculture Department, is the U.S. federal executive department responsible for developing and executing federal laws related to farming, forestry, and food.

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Universal Time

Universal Time (UT) is a time standard based on Earth's rotation.

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Unix time

Unix time (also known as POSIX time or UNIX Epoch time) is a system for describing a point in time, defined as the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970,.

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Variable star

A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates.

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Water clock

A water clock or clepsydra (Greek κλεψύδρα from κλέπτειν kleptein, 'to steal'; ὕδωρ hydor, 'water') is any timepiece in which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel where the amount is then measured.

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A week is a time unit equal to seven days.

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Zeller's congruence

Zeller's congruence is an algorithm devised by Christian Zeller to calculate the day of the week for any Julian or Gregorian calendar date.

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.NET strategy

The.NET strategy was a long-term Microsoft software development and marketing plan, envisioned in late 1990s.

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5th millennium BC

The 5th millennium BC spanned the years 5000 through 4001 BC.

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11/17/1858, 17-Nov-1858, Julian Date, Julian Day Number, Julian Day Numbers, Julian Period, Julian date, Julian date calendar, Julian day number, Modified Julian Date, Modified Julian Day, Modified Julian date, Modified Julian day, Reduced Julian Day, Reduced Julian date, Scalinger number, Truncated Julian day.


[1] https://en.wikipedia.org/wiki/Julian_day

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