Package gavo :: Package stc :: Module times

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Module times

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Helpers for time parsing and conversion.

Functions

parseISODT(value)

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jdnToDateTime(jd)
returns a ``datetime.datetime`` instance for a julian day number.

source code

mjdToDateTime(mjd)
returns a ``datetime.datetime`` instance for a modified julian day number.

source code

bYearToDateTime(bYear)
returns a datetime.datetime instance for a fractional Besselian year.

source code

jYearToDateTime(jYear)
returns a datetime.datetime instance for a fractional (julian) year.

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dateTimeToJdn(dt)
returns a julian day number (including fractionals) from a datetime instance.

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dateTimeToMJD(dt)
returns a modified julian date for a datetime instance.

source code

dateTimeToBYear(dt)

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dateTimeToJYear(dt)
returns a fractional (julian) year for a datetime.datetime instance.

source code

getSeconds(td)
returns the number of seconds corresponding to a timedelta object.

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TTtoTAI(tdt)
returns TAI for a (datetime.datetime) TDT.

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TAItoTT(tai)
returns TDT for a (datetime.datetime) TAI.

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TDBtoTT(tdb)
returns an approximate TT from a TDB.

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TTtoTDB(tt)
returns approximate TDB from TT.

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TTtoTCG(tt)
returns TT from TCG.

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TCGtoTT(tcg)
returns TT from TCG.

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TCBtoTT(tcb)
returns an approximate TCB from a TT.

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TTtoTCB(tt)
returns an approximate TT from a TCB.

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getLeapSeconds(dt, table=[(datetime.datetime(1971, 12, 31, 23, 59, 59), datetime.timede...)
returns TAI-UTC for the datetime dt. source code

UTCtoTT(utc)
returns TT from UTC.

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TTtoUTC(tt)
returns UTC from TT.

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getTransformFromScales(fromScale, toScale)

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getTransformFromSTC(fromSTC, toSTC)

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datetimeMapperFactory(colDesc)

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Variables
	JD_MJD = `2400000.5`
	dtJ2000 = `datetime.datetime(2000, 1, 1, 12, 0)`
	dtB1950 = `datetime.datetime(1949, 12, 31, 22, 9, 46, 861900)`
	leapSecondTable = `[(datetime.datetime(1971, 12, 31, 23, 59, 59...`
	ttLeapSecondTable = `[(datetime.datetime(1971, 12, 31, 23, 59, ...`
	timeConversions = `{'TAI': (<__builtin__.function object>, <__b...`
	__package__ = `'gavo.stc'`
	dt = `datetime.timedelta(0, 34)`
	t = `datetime.datetime(2008, 12, 31, 23, 59, 59)`

Function Details

jdnToDateTime(jd)

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returns a ``datetime.datetime`` instance for a julian day number.

Decorators:

@utils.document

mjdToDateTime(mjd)

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returns a ``datetime.datetime`` instance for a modified julian day number.

Beware: This loses a couple of significant digits due to transformation to jd.

Decorators:

@utils.document

bYearToDateTime(bYear)

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returns a datetime.datetime instance for a fractional Besselian year.

This uses the formula given by Lieske, J.H., A&A 73, 282 (1979).

Decorators:

@utils.document

jYearToDateTime(jYear)

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returns a datetime.datetime instance for a fractional (julian) year.

This refers to time specifications like J2001.32.

Decorators:

@utils.document

dateTimeToJdn(dt)

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returns a julian day number (including fractionals) from a datetime instance.

Decorators:

@utils.document

dateTimeToMJD(dt)

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returns a modified julian date for a datetime instance.

Decorators:

@utils.document

dateTimeToJYear(dt)

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returns a fractional (julian) year for a datetime.datetime instance.

Decorators:

@utils.document

TTtoTAI(tdt)

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returns TAI for a (datetime.datetime) TDT.

Decorators:

@utils.document

TAItoTT(tai)

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returns TDT for a (datetime.datetime) TAI.

Decorators:

@utils.document

TDBtoTT(tdb)

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returns an approximate TT from a TDB.

The simplified formula 2.222-1 from [EXS] is used.

TTtoTDB(tt)

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returns approximate TDB from TT.

The simplified formula 2.222-1 from [EXS] is used.

TTtoTCG(tt)

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returns TT from TCG.

This uses 2.223-5 from [EXS].

TCGtoTT(tcg)

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returns TT from TCG.

This uses 2.223-5 from [EXS].

TCBtoTT(tcb)

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returns an approximate TCB from a TT.

This uses [EXS] 2.223-2 and the approximate conversion from TDB to TT.

TTtoTCB(tt)

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returns an approximate TT from a TCB.

This uses [EXS] 2.223-2 and the approximate conversion from TT to TDB.

UTCtoTT(utc)

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returns TT from UTC.

The leap second table is complete through 2009-5.

>>> getLeapSeconds(datetime.datetime(1998,12,31,23,59,58))
datetime.timedelta(0, 31)
>>> TTtoTAI(UTCtoTT(datetime.datetime(1998,12,31,23,59,59)))
datetime.datetime(1999, 1, 1, 0, 0, 30)
>>> TTtoTAI(UTCtoTT(datetime.datetime(1999,1,1,0,0,0)))
datetime.datetime(1999, 1, 1, 0, 0, 32)

TTtoUTC(tt)

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returns UTC from TT.

The leap second table is complete through 2009-5.

>>> TTtoUTC(UTCtoTT(datetime.datetime(1998,12,31,23,59,59)))
datetime.datetime(1998, 12, 31, 23, 59, 59)
>>> TTtoUTC(UTCtoTT(datetime.datetime(1999,1,1,0,0,0)))
datetime.datetime(1999, 1, 1, 0, 0)

Variables Details

leapSecondTable

Value:

[(datetime.datetime(1971, 12, 31, 23, 59, 59),
  datetime.timedelta(0, 10)),
 (datetime.datetime(1972, 6, 30, 23, 59, 59),
  datetime.timedelta(0, 11)),
 (datetime.datetime(1972, 12, 31, 23, 59, 59),
  datetime.timedelta(0, 12)),
 (datetime.datetime(1973, 12, 31, 23, 59, 59),
  datetime.timedelta(0, 13)),
...

ttLeapSecondTable

Value:

[(datetime.datetime(1971, 12, 31, 23, 59, 35, 816000),
  datetime.timedelta(0, 10)),
 (datetime.datetime(1972, 6, 30, 23, 59, 36, 816000),
  datetime.timedelta(0, 11)),
 (datetime.datetime(1972, 12, 31, 23, 59, 37, 816000),
  datetime.timedelta(0, 12)),
 (datetime.datetime(1973, 12, 31, 23, 59, 38, 816000),
  datetime.timedelta(0, 13)),
...

timeConversions

Value:

{'TAI': (<__builtin__.function object>, <__builtin__.function object>)
,
 'TCB': (<__builtin__.function object>, <__builtin__.function object>)
,
 'TCG': (<__builtin__.function object>, <__builtin__.function object>)
,
 'TDB': (<__builtin__.function object>, <__builtin__.function object>)
,
...