org.orekit.time

Class UTCScale

java.lang.Object

org.orekit.time.UTCScale

All Implemented Interfaces:

Serializable, TimeScale

public class UTCScale
extends Object
implements TimeScale

Coordinated Universal Time.

UTC is related to TAI using step adjustments from time to time according to IERS (International Earth Rotation Service) rules. Before 1972, these adjustments were piecewise linear offsets. Since 1972, these adjustments are piecewise constant offsets, which require introduction of leap seconds.

Leap seconds are always inserted as additional seconds at the last minute of the day, pushing the next day forward. Such minutes are therefore more than 60 seconds long. In theory, there may be seconds removal instead of seconds insertion, but up to now (2010) it has never been used. As an example, when a one second leap was introduced at the end of 2005, the UTC time sequence was 2005-12-31T23:59:59 UTC, followed by 2005-12-31T23:59:60 UTC, followed by 2006-01-01T00:00:00 UTC.

This is intended to be accessed thanks to TimeScales, so there is no public constructor.

Author:

Luc Maisonobe

See Also:

AbsoluteDate, Serialized Form

Method Summary

Modifier and Type	Method and Description
AbsoluteDate	getFirstKnownLeapSecond() Get the date of the first known leap second.
AbsoluteDate	getLastKnownLeapSecond() Get the date of the last known leap second.
double	getLeap(AbsoluteDate date) Get the value of the previous leap.
<T extends CalculusFieldElement<T>> T	getLeap(FieldAbsoluteDate<T> date) Get the value of the previous leap.
String	getName() Get the name time scale.
List<UTCTAIOffset>	getUTCTAIOffsets() Returns the UTC-TAI offsets underlying this UTC scale.
boolean	insideLeap(AbsoluteDate date) Check if date is within a leap second introduction in this time scale.
<T extends CalculusFieldElement<T>> boolean	insideLeap(FieldAbsoluteDate<T> date) Check if date is within a leap second introduction in this time scale.
int	minuteDuration(AbsoluteDate date) Check length of the current minute in this time scale.
<T extends CalculusFieldElement<T>> int	minuteDuration(FieldAbsoluteDate<T> date) Check length of the current minute in this time scale.
double	offsetFromTAI(AbsoluteDate date) Get the offset to convert locations from TAIScale to instance.
<T extends CalculusFieldElement<T>> T	offsetFromTAI(FieldAbsoluteDate<T> date) Get the offset to convert locations from TAIScale to instance.
double	offsetToTAI(DateComponents date, TimeComponents time) Get the offset to convert locations from instance to TAIScale.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getUTCTAIOffsets

public List<UTCTAIOffset> getUTCTAIOffsets()

Returns the UTC-TAI offsets underlying this UTC scale.

Modifications to the returned list will not affect this UTC scale instance.

Returns:

new non-null modifiable list of UTC-TAI offsets time-sorted from earliest to latest

offsetFromTAI

public double offsetFromTAI(AbsoluteDate date)

Get the offset to convert locations from TAIScale to instance.

Specified by:

offsetFromTAI in interface TimeScale

Parameters:

date - conversion date

Returns:

offset in seconds to add to a location in TAIScale time scale to get a location in instance time scale

See Also:

TimeScale.offsetToTAI(DateComponents, TimeComponents)

offsetFromTAI

public <T extends CalculusFieldElement<T>> T offsetFromTAI(FieldAbsoluteDate<T> date)

Get the offset to convert locations from TAIScale to instance.

Specified by:

offsetFromTAI in interface TimeScale

Type Parameters:

T - type of the filed elements

Parameters:

date - conversion date

Returns:

offset in seconds to add to a location in TAIScale time scale to get a location in instance time scale

See Also:

TimeScale.offsetToTAI(DateComponents, TimeComponents)

offsetToTAI

public double offsetToTAI(DateComponents date,
                          TimeComponents time)

Get the offset to convert locations from instance to TAIScale.

Specified by:

offsetToTAI in interface TimeScale

Parameters:

date - date location in the time scale

time - time location in the time scale

Returns:

offset in seconds to add to a location in instance time scale to get a location in TAIScale time scale

See Also:

TimeScale.offsetFromTAI(AbsoluteDate)

getName

public String getName()

Get the name time scale.

Specified by:

getName in interface TimeScale

Returns:

name of the time scale

toString

public String toString()

Overrides:

toString in class Object

getFirstKnownLeapSecond

public AbsoluteDate getFirstKnownLeapSecond()

Get the date of the first known leap second.

Returns:

date of the first known leap second

getLastKnownLeapSecond

public AbsoluteDate getLastKnownLeapSecond()

Get the date of the last known leap second.

Returns:

date of the last known leap second

insideLeap

public boolean insideLeap(AbsoluteDate date)

Check if date is within a leap second introduction in this time scale.

This method will return false for all time scales that do not implement leap seconds, even if the date corresponds to a leap second in UTC scale.

Specified by:

insideLeap in interface TimeScale

Parameters:

date - date to check

Returns:

true if time is within a leap second introduction

insideLeap

public <T extends CalculusFieldElement<T>> boolean insideLeap(FieldAbsoluteDate<T> date)

Check if date is within a leap second introduction in this time scale.

This method will return false for all time scales that do not implement leap seconds, even if the date corresponds to a leap second in UTC scale.

Specified by:

insideLeap in interface TimeScale

Type Parameters:

T - type of the filed elements

Parameters:

date - date to check

Returns:

true if time is within a leap second introduction

minuteDuration

public int minuteDuration(AbsoluteDate date)

Check length of the current minute in this time scale.

This method will return 60 for all time scales that do not implement leap seconds, even if the date corresponds to a leap second in UTC scale, and 61 for time scales that do implement leap second when the current date is within the last minute before the leap, or during the leap itself.

Specified by:

minuteDuration in interface TimeScale

Parameters:

date - date to check

Returns:

60 or 61 depending on leap seconds introduction

minuteDuration

public <T extends CalculusFieldElement<T>> int minuteDuration(FieldAbsoluteDate<T> date)

Check length of the current minute in this time scale.

This method will return 60 for all time scales that do not implement leap seconds, even if the date corresponds to a leap second in UTC scale, and 61 for time scales that do implement leap second when the current date is within the last minute before the leap, or during the leap itself.

Specified by:

minuteDuration in interface TimeScale

Type Parameters:

T - type of the filed elements

Parameters:

date - date to check

Returns:

60 or 61 depending on leap seconds introduction

getLeap

public double getLeap(AbsoluteDate date)

Get the value of the previous leap.

This method will return 0.0 for all time scales that do not implement leap seconds.

Specified by:

getLeap in interface TimeScale

Parameters:

date - date to check

Returns:

value of the previous leap

getLeap

public <T extends CalculusFieldElement<T>> T getLeap(FieldAbsoluteDate<T> date)

Get the value of the previous leap.

This method will return 0.0 for all time scales that do not implement leap seconds.

Specified by:

getLeap in interface TimeScale

Type Parameters:

T - type of the filed elements

Parameters:

date - date to check

Returns:

value of the previous leap