View source for JD2Dt

{{DavinciWiki_Function|
Convert UTC Julian date to J2000.0 TT offset (accounts for leap seconds)
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Parameters: Numeric array specifying the UTC Julian Dates to convert to J2000.0 TT offsets

Return Value: The corresponding set of J2000.0 TT offsets (in days)
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[[Syntax]]: JD2Dt(JD)

The Julian Date (JD) is a continuous count of days since noon UTC on January 1, 4713 BCE in the proleptic Julian calendar.

The J2000.0 TT offset (&Delta;t<sub>J2000</sub>) is a continuous count of days since noon TT on January 1, 2000. This offset is the input to [[marstimeglobal]].

Coordinated Universal Time (UTC) is the basis for the time system used in everyday life. In order to keep UTC consistent with the Earth's slightly variable rate of rotation, leap seconds are occasionally inserted into UTC. Terrestrial Time (TT) is a time system with no leap seconds.

Returns double-precision J2000.0 TT offsets. The returned values are as accurate as the input, although that accuracy may be further limited by uncertainty in Delta-T. See the function [[DeltaT]] for details.

For more information, see http://heasarc.gsfc.nasa.gov/docs/xte/abc/time_tutorial.html and http://www.giss.nasa.gov/tools/mars24/help/algorithm.html.

When JD2Dt() is entered without any arguments, it prints its description, as shown below.
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 dv> JD2Dt()
 
 Convert UTC Julian date to J2000.0 TT offset
 JD2Dt(JD) returns number of days since noon TT on January 1, 2000
 Accounts for leap seconds
 Works for array inputs
 Returns double-precision offset, in days
 The returned values are as accurate as the input, although that
 accuracy may be further limited by uncertainty in Delta-T. See
 the function DeltaT for details.
 See http://www.giss.nasa.gov/tools/mars24/help/algorithm.html
 S.Marshall 06-29-2008
 
 0
 dv> a &#61; JD(2010, 1, 1, 12, 0, 0)
 2455198.00000000
 dv> JD2Dt(a)
 3653.00076601841
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*[[JD2TT]]
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*[[clock]]
*[[DeltaT]]
*[[earthtime]]
*[[JD]]
*[[JD2ET]]
*[[JD2TT]]
*[[marstimeglobal]]
*[[MJD2Dt]]
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1.15
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[[category:Functions|{{lcfirst:{{uc:{{PAGENAME}}}}}}]]
[[category:User Defined Functions|{{lcfirst:{{uc:{{PAGENAME}}}}}}]]
[[category:Time|{{lcfirst:{{uc:{{PAGENAME}}}}}}]]