org.orekit.time

Class AbsoluteDate

java.lang.Object

org.orekit.time.AbsoluteDate

All Implemented Interfaces:

Serializable, Comparable<AbsoluteDate>, TimeShiftable<AbsoluteDate>, TimeStamped

public class AbsoluteDate
extends Object
implements TimeStamped, TimeShiftable<AbsoluteDate>, Comparable<AbsoluteDate>, Serializable

This class represents a specific instant in time.

Instances of this class are considered to be absolute in the sense that each one represent the occurrence of some event and can be compared to other instances or located in any time scale. In other words the different locations of an event with respect to two different time scales (say TAI and UTC for example) are simply different perspective related to a single object. Only one AbsoluteDate instance is needed, both representations being available from this single instance by specifying the time scales as parameter when calling the ad-hoc methods.

Since an instance is not bound to a specific time-scale, all methods related to the location of the date within some time scale require to provide the time scale as an argument. It is therefore possible to define a date in one time scale and to use it in another one. An example of such use is to read a date from a file in UTC and write it in another file in TAI. This can be done as follows:

   DateTimeComponents utcComponents = readNextDate();
   AbsoluteDate date = new AbsoluteDate(utcComponents, TimeScalesFactory.getUTC());
   writeNextDate(date.getComponents(TimeScalesFactory.getTAI()));
 

Two complementary views are available:

• location view (mainly for input/output or conversions)

  locations represent the coordinate of one event with respect to a time scale. The related methods are AbsoluteDate(DateComponents, TimeComponents, TimeScale), AbsoluteDate(int, int, int, int, int, double, TimeScale), AbsoluteDate(int, int, int, TimeScale), AbsoluteDate(Date, TimeScale), parseCCSDSCalendarSegmentedTimeCode(byte, byte[]), toDate(TimeScale), toString(timeScale), toString(), and timeScalesOffset(org.orekit.time.TimeScale, org.orekit.time.TimeScale).

• offset view (mainly for physical computation)

  offsets represent either the flow of time between two events (two instances of the class) or durations. They are counted in seconds, are continuous and could be measured using only a virtually perfect stopwatch. The related methods are AbsoluteDate(AbsoluteDate, double), parseCCSDSUnsegmentedTimeCode(byte, byte, byte[], AbsoluteDate), parseCCSDSDaySegmentedTimeCode(byte, byte[], DateComponents), durationFrom(AbsoluteDate), compareTo(AbsoluteDate), equals(Object) and hashCode().

A few reference epochs which are commonly used in space systems have been defined. These epochs can be used as the basis for offset computation. The supported epochs are: JULIAN_EPOCH, MODIFIED_JULIAN_EPOCH, FIFTIES_EPOCH, CCSDS_EPOCH, GALILEO_EPOCH, GPS_EPOCH, QZSS_EPOCH J2000_EPOCH, JAVA_EPOCH. There are also two factory methods createJulianEpoch(double) and createBesselianEpoch(double) that can be used to compute other reference epochs like J1900.0 or B1950.0. In addition to these reference epochs, two other constants are defined for convenience: PAST_INFINITY and FUTURE_INFINITY, which can be used either as dummy dates when a date is not yet initialized, or for initialization of loops searching for a min or max date.

Instances of the AbsoluteDate class are guaranteed to be immutable.

Author:

Luc Maisonobe, Evan Ward

See Also:

TimeScale, TimeStamped, ChronologicalComparator, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static AbsoluteDate	ARBITRARY_EPOCH An arbitrary finite date.
static AbsoluteDate	BEIDOU_EPOCH Reference epoch for BeiDou weeks: 2006-01-01T00:00:00 UTC.
static AbsoluteDate	CCSDS_EPOCH Reference epoch for CCSDS Time Code Format (CCSDS 301.0-B-4): 1958-01-01T00:00:00 International Atomic Time (not UTC).
static AbsoluteDate	FIFTIES_EPOCH Reference epoch for 1950 dates: 1950-01-01T00:00:00 Terrestrial Time.
static AbsoluteDate	FUTURE_INFINITY Dummy date at infinity in the future direction.
static AbsoluteDate	GALILEO_EPOCH Reference epoch for Galileo System Time: 1999-08-22T00:00:00 GST.
static AbsoluteDate	GLONASS_EPOCH Reference epoch for GLONASS four-year interval number: 1996-01-01T00:00:00 GLONASS time.
static AbsoluteDate	GPS_EPOCH Reference epoch for GPS weeks: 1980-01-06T00:00:00 GPS time.
static AbsoluteDate	IRNSS_EPOCH Reference epoch for IRNSS weeks: 1999-08-22T00:00:00 IRNSS time.
static AbsoluteDate	J2000_EPOCH J2000.0 Reference epoch: 2000-01-01T12:00:00 Terrestrial Time (not UTC).
static AbsoluteDate	JAVA_EPOCH Java Reference epoch: 1970-01-01T00:00:00 Universal Time Coordinate.
static AbsoluteDate	JULIAN_EPOCH Reference epoch for julian dates: -4712-01-01T12:00:00 Terrestrial Time.
static AbsoluteDate	MODIFIED_JULIAN_EPOCH Reference epoch for modified julian dates: 1858-11-17T00:00:00 Terrestrial Time.
static AbsoluteDate	PAST_INFINITY Dummy date at infinity in the past direction.
static AbsoluteDate	QZSS_EPOCH Reference epoch for QZSS weeks: 1980-01-06T00:00:00 QZSS time.

Constructor Summary

Constructors

Constructor and Description
AbsoluteDate() Create an instance with a default value (J2000_EPOCH).
AbsoluteDate(AbsoluteDate since, double elapsedDuration) Build an instance from an elapsed duration since to another instant.
AbsoluteDate(AbsoluteDate reference, double apparentOffset, TimeScale timeScale) Build an instance from an apparent clock offset with respect to another instant in the perspective of a specific time scale.
AbsoluteDate(DateComponents date, TimeComponents time, TimeScale timeScale) Build an instance from a location in a time scale.
AbsoluteDate(DateComponents date, TimeScale timeScale) Build an instance from a location in a time scale.
AbsoluteDate(DateTimeComponents location, TimeScale timeScale) Build an instance from a location in a time scale.
AbsoluteDate(Date location, TimeScale timeScale) Build an instance from a location in a time scale.
AbsoluteDate(int year, int month, int day, int hour, int minute, double second, TimeScale timeScale) Build an instance from a location in a time scale.
AbsoluteDate(int year, int month, int day, TimeScale timeScale) Build an instance from a location in a time scale.
AbsoluteDate(int year, Month month, int day, int hour, int minute, double second, TimeScale timeScale) Build an instance from a location in a time scale.
AbsoluteDate(int year, Month month, int day, TimeScale timeScale) Build an instance from a location in a time scale.
AbsoluteDate(String location, TimeScale timeScale) Build an instance from a location (parsed from a string) in a time scale.

Method Summary

Modifier and Type	Method and Description
int	compareTo(AbsoluteDate date) Compare the instance with another date.
static AbsoluteDate	createBesselianEpoch(double besselianEpoch) Build an instance corresponding to a Besselian Epoch (BE).
static AbsoluteDate	createJDDate(int jd, double secondsSinceNoon, TimeScale timeScale) Build an instance corresponding to a Julian Day date.
static AbsoluteDate	createJulianEpoch(double julianEpoch) Build an instance corresponding to a Julian Epoch (JE).
static AbsoluteDate	createMJDDate(int mjd, double secondsInDay, TimeScale timeScale) Build an instance corresponding to a Modified Julian Day date.
double	durationFrom(AbsoluteDate instant) Compute the physically elapsed duration between two instants.
boolean	equals(Object date) Check if the instance represents the same time as another instance.
DateTimeComponents	getComponents(int minutesFromUTC) Split the instance into date/time components for a local time.
DateTimeComponents	getComponents(int minutesFromUTC, TimeScale utc) Split the instance into date/time components for a local time.
DateTimeComponents	getComponents(TimeScale timeScale) Split the instance into date/time components.
DateTimeComponents	getComponents(TimeZone timeZone) Split the instance into date/time components for a time zone.
DateTimeComponents	getComponents(TimeZone timeZone, TimeScale utc) Split the instance into date/time components for a time zone.
AbsoluteDate	getDate() Get the date.
int	hashCode() Get a hashcode for this date.
boolean	isAfter(TimeStamped other) Check if the instance represents a time that is strictly after another.
boolean	isAfterOrEqualTo(TimeStamped other) Check if the instance represents a time that is after or equal to another.
boolean	isBefore(TimeStamped other) Check if the instance represents a time that is strictly before another.
boolean	isBeforeOrEqualTo(TimeStamped other) Check if the instance represents a time that is before or equal to another.
boolean	isBetween(TimeStamped boundary, TimeStamped otherBoundary) Check if the instance represents a time that is strictly between two others representing the boundaries of a time span.
boolean	isBetweenOrEqualTo(TimeStamped boundary, TimeStamped otherBoundary) Check if the instance represents a time that is between two others representing the boundaries of a time span, or equal to one of them.
boolean	isCloseTo(TimeStamped other, double tolerance) Check if the instance time is close to another.
boolean	isEqualTo(TimeStamped other) Check if the instance represents the same time as another.
double	offsetFrom(AbsoluteDate instant, TimeScale timeScale) Compute the apparent clock offset between two instant in the perspective of a specific time scale.
static AbsoluteDate	parseCCSDSCalendarSegmentedTimeCode(byte preambleField, byte[] timeField) Build an instance from a CCSDS Calendar Segmented Time Code (CCS).
static AbsoluteDate	parseCCSDSCalendarSegmentedTimeCode(byte preambleField, byte[] timeField, TimeScale utc) Build an instance from a CCSDS Calendar Segmented Time Code (CCS).
static AbsoluteDate	parseCCSDSDaySegmentedTimeCode(byte preambleField, byte[] timeField, DateComponents agencyDefinedEpoch) Build an instance from a CCSDS Day Segmented Time Code (CDS).
static AbsoluteDate	parseCCSDSDaySegmentedTimeCode(byte preambleField, byte[] timeField, DateComponents agencyDefinedEpoch, TimeScale utc) Build an instance from a CCSDS Day Segmented Time Code (CDS).
static AbsoluteDate	parseCCSDSUnsegmentedTimeCode(byte preambleField1, byte preambleField2, byte[] timeField, AbsoluteDate agencyDefinedEpoch) Build an instance from a CCSDS Unsegmented Time Code (CUC).
static AbsoluteDate	parseCCSDSUnsegmentedTimeCode(byte preambleField1, byte preambleField2, byte[] timeField, AbsoluteDate agencyDefinedEpoch, AbsoluteDate ccsdsEpoch) Build an instance from a CCSDS Unsegmented Time Code (CUC).
AbsoluteDate	shiftedBy(double dt) Get a time-shifted date.
double	timeScalesOffset(TimeScale scale1, TimeScale scale2) Compute the offset between two time scales at the current instant.
Date	toDate(TimeScale timeScale) Convert the instance to a Java Date.
String	toString() Get a String representation of the instant location in UTC time scale.
String	toString(int minutesFromUTC) Get a String representation of the instant location for a local time.
String	toString(int minutesFromUTC, TimeScale utc) Get a String representation of the instant location for a local time.
String	toString(TimeScale timeScale) Get a String representation of the instant location.
String	toString(TimeZone timeZone) Get a String representation of the instant location for a time zone.
String	toString(TimeZone timeZone, TimeScale utc) Get a String representation of the instant location for a time zone.
String	toStringRfc3339(TimeScale utc) Represent the given date as a string according to the format in RFC 3339.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

JULIAN_EPOCH

@DefaultDataContext
public static final AbsoluteDate JULIAN_EPOCH

Reference epoch for julian dates: -4712-01-01T12:00:00 Terrestrial Time.

Both java.util.Date and DateComponents classes follow the astronomical conventions and consider a year 0 between years -1 and +1, hence this reference date lies in year -4712 and not in year -4713 as can be seen in other documents or programs that obey a different convention (for example the convcal utility).

This constant uses the default data context.

See Also:

TimeScales.getJulianEpoch()

MODIFIED_JULIAN_EPOCH

@DefaultDataContext
public static final AbsoluteDate MODIFIED_JULIAN_EPOCH

Reference epoch for modified julian dates: 1858-11-17T00:00:00 Terrestrial Time.

This constant uses the default data context.

See Also:

TimeScales.getModifiedJulianEpoch()

FIFTIES_EPOCH

@DefaultDataContext
public static final AbsoluteDate FIFTIES_EPOCH

Reference epoch for 1950 dates: 1950-01-01T00:00:00 Terrestrial Time.

This constant uses the default data context.

See Also:

TimeScales.getFiftiesEpoch()

CCSDS_EPOCH

@DefaultDataContext
public static final AbsoluteDate CCSDS_EPOCH

Reference epoch for CCSDS Time Code Format (CCSDS 301.0-B-4): 1958-01-01T00:00:00 International Atomic Time (not UTC).

This constant uses the default data context.

See Also:

TimeScales.getCcsdsEpoch()

GALILEO_EPOCH

@DefaultDataContext
public static final AbsoluteDate GALILEO_EPOCH

Reference epoch for Galileo System Time: 1999-08-22T00:00:00 GST.

This constant uses the default data context.

See Also:

TimeScales.getGalileoEpoch()

GPS_EPOCH

@DefaultDataContext
public static final AbsoluteDate GPS_EPOCH

Reference epoch for GPS weeks: 1980-01-06T00:00:00 GPS time.

This constant uses the default data context.

See Also:

TimeScales.getGpsEpoch()

QZSS_EPOCH

@DefaultDataContext
public static final AbsoluteDate QZSS_EPOCH

Reference epoch for QZSS weeks: 1980-01-06T00:00:00 QZSS time.

This constant uses the default data context.

See Also:

TimeScales.getQzssEpoch()

IRNSS_EPOCH

@DefaultDataContext
public static final AbsoluteDate IRNSS_EPOCH

Reference epoch for IRNSS weeks: 1999-08-22T00:00:00 IRNSS time.

This constant uses the default data context.

See Also:

TimeScales.getIrnssEpoch()

BEIDOU_EPOCH

@DefaultDataContext
public static final AbsoluteDate BEIDOU_EPOCH

Reference epoch for BeiDou weeks: 2006-01-01T00:00:00 UTC.

This constant uses the default data context.

See Also:

TimeScales.getBeidouEpoch()

GLONASS_EPOCH

@DefaultDataContext
public static final AbsoluteDate GLONASS_EPOCH

Reference epoch for GLONASS four-year interval number: 1996-01-01T00:00:00 GLONASS time.

By convention, TGLONASS = UTC + 3 hours.

This constant uses the default data context.

See Also:

TimeScales.getGlonassEpoch()

J2000_EPOCH

@DefaultDataContext
public static final AbsoluteDate J2000_EPOCH

J2000.0 Reference epoch: 2000-01-01T12:00:00 Terrestrial Time (not UTC).

See Also:

createJulianEpoch(double),

This constant uses the {@link DataContext#getDefault() default data context}., TimeScales.getJ2000Epoch()

JAVA_EPOCH

@DefaultDataContext
public static final AbsoluteDate JAVA_EPOCH

Java Reference epoch: 1970-01-01T00:00:00 Universal Time Coordinate.

Between 1968-02-01 and 1972-01-01, UTC-TAI = 4.213 170 0s + (MJD - 39 126) x 0.002 592s. As on 1970-01-01 MJD = 40587, UTC-TAI = 8.000082s

This constant uses the default data context.

See Also:

TimeScales.getJavaEpoch()

ARBITRARY_EPOCH

public static final AbsoluteDate ARBITRARY_EPOCH

An arbitrary finite date. Uses when a non-null date is needed but its value doesn't matter.

PAST_INFINITY

public static final AbsoluteDate PAST_INFINITY

Dummy date at infinity in the past direction.

See Also:

TimeScales.getPastInfinity()

FUTURE_INFINITY

public static final AbsoluteDate FUTURE_INFINITY

Dummy date at infinity in the future direction.

See Also:

TimeScales.getFutureInfinity()

Constructor Detail

AbsoluteDate

@DefaultDataContext
public AbsoluteDate()

Create an instance with a default value (J2000_EPOCH).

This constructor uses the default data context.

See Also:

AbsoluteDate(DateTimeComponents, TimeScale)

AbsoluteDate

public AbsoluteDate(String location,
                    TimeScale timeScale)

Build an instance from a location (parsed from a string) in a time scale.

The supported formats for location are mainly the ones defined in ISO-8601 standard, the exact subset is explained in DateTimeComponents.parseDateTime(String), DateComponents.parseDate(String) and TimeComponents.parseTime(String).

As CCSDS ASCII calendar segmented time code is a trimmed down version of ISO-8601, it is also supported by this constructor.

Parameters:

location - location in the time scale, must be in a supported format

timeScale - time scale

Throws:

IllegalArgumentException - if location string is not in a supported format

AbsoluteDate

public AbsoluteDate(DateTimeComponents location,
                    TimeScale timeScale)

Build an instance from a location in a time scale.

Parameters:

location - location in the time scale

timeScale - time scale

AbsoluteDate

public AbsoluteDate(DateComponents date,
                    TimeComponents time,
                    TimeScale timeScale)

Build an instance from a location in a time scale.

Parameters:

date - date location in the time scale

time - time location in the time scale

timeScale - time scale

AbsoluteDate

public AbsoluteDate(int year,
                    int month,
                    int day,
                    int hour,
                    int minute,
                    double second,
                    TimeScale timeScale)
             throws IllegalArgumentException

Build an instance from a location in a time scale.

Parameters:

year - year number (may be 0 or negative for BC years)

month - month number from 1 to 12

day - day number from 1 to 31

hour - hour number from 0 to 23

minute - minute number from 0 to 59

second - second number from 0.0 to 60.0 (excluded)

timeScale - time scale

Throws:

IllegalArgumentException - if inconsistent arguments are given (parameters out of range)

AbsoluteDate

public AbsoluteDate(int year,
                    Month month,
                    int day,
                    int hour,
                    int minute,
                    double second,
                    TimeScale timeScale)
             throws IllegalArgumentException

Build an instance from a location in a time scale.

Parameters:

year - year number (may be 0 or negative for BC years)

month - month enumerate

day - day number from 1 to 31

hour - hour number from 0 to 23

minute - minute number from 0 to 59

second - second number from 0.0 to 60.0 (excluded)

timeScale - time scale

Throws:

IllegalArgumentException - if inconsistent arguments are given (parameters out of range)

AbsoluteDate

public AbsoluteDate(DateComponents date,
                    TimeScale timeScale)
             throws IllegalArgumentException

Build an instance from a location in a time scale.

The hour is set to 00:00:00.000.

Parameters:

date - date location in the time scale

timeScale - time scale

Throws:

IllegalArgumentException - if inconsistent arguments are given (parameters out of range)

AbsoluteDate

public AbsoluteDate(int year,
                    int month,
                    int day,
                    TimeScale timeScale)
             throws IllegalArgumentException

Build an instance from a location in a time scale.

The hour is set to 00:00:00.000.

Parameters:

year - year number (may be 0 or negative for BC years)

month - month number from 1 to 12

day - day number from 1 to 31

timeScale - time scale

Throws:

IllegalArgumentException - if inconsistent arguments are given (parameters out of range)

AbsoluteDate

public AbsoluteDate(int year,
                    Month month,
                    int day,
                    TimeScale timeScale)
             throws IllegalArgumentException

Build an instance from a location in a time scale.

The hour is set to 00:00:00.000.

Parameters:

year - year number (may be 0 or negative for BC years)

month - month enumerate

day - day number from 1 to 31

timeScale - time scale

Throws:

IllegalArgumentException - if inconsistent arguments are given (parameters out of range)

AbsoluteDate

public AbsoluteDate(Date location,
                    TimeScale timeScale)

Build an instance from a location in a time scale.

Parameters:

location - location in the time scale

timeScale - time scale

AbsoluteDate

public AbsoluteDate(AbsoluteDate since,
                    double elapsedDuration)

Build an instance from an elapsed duration since to another instant.

It is important to note that the elapsed duration is not the difference between two readings on a time scale. As an example, the duration between the two instants leading to the readings 2005-12-31T23:59:59 and 2006-01-01T00:00:00 in the UTC time scale is not 1 second, but a stop watch would have measured an elapsed duration of 2 seconds between these two instances because a leap second was introduced at the end of 2005 in this time scale.

This constructor is the reverse of the durationFrom(AbsoluteDate) method.

Parameters:

since - start instant of the measured duration

elapsedDuration - physically elapsed duration from the since instant, as measured in a regular time scale

See Also:

durationFrom(AbsoluteDate)

AbsoluteDate

public AbsoluteDate(AbsoluteDate reference,
                    double apparentOffset,
                    TimeScale timeScale)

Build an instance from an apparent clock offset with respect to another instant in the perspective of a specific time scale.

It is important to note that the apparent clock offset is the difference between two readings on a time scale and not an elapsed duration. As an example, the apparent clock offset between the two instants leading to the readings 2005-12-31T23:59:59 and 2006-01-01T00:00:00 in the UTC time scale is 1 second, but the elapsed duration is 2 seconds because a leap second has been introduced at the end of 2005 in this time scale.

This constructor is the reverse of the offsetFrom(AbsoluteDate, TimeScale) method.

Parameters:

reference - reference instant

apparentOffset - apparent clock offset from the reference instant (difference between two readings in the specified time scale)

timeScale - time scale with respect to which the offset is defined

See Also:

offsetFrom(AbsoluteDate, TimeScale)

Method Detail

parseCCSDSUnsegmentedTimeCode

@DefaultDataContext
public static AbsoluteDate parseCCSDSUnsegmentedTimeCode(byte preambleField1,
                                                                             byte preambleField2,
                                                                             byte[] timeField,
                                                                             AbsoluteDate agencyDefinedEpoch)

Build an instance from a CCSDS Unsegmented Time Code (CUC).

CCSDS Unsegmented Time Code is defined in the blue book: CCSDS Time Code Format (CCSDS 301.0-B-4) published in November 2010

If the date to be parsed is formatted using version 3 of the standard (CCSDS 301.0-B-3 published in 2002) or if the extension of the preamble field introduced in version 4 of the standard is not used, then the preambleField2 parameter can be set to 0.

This method uses the default data context if the CCSDS epoch is used.

Parameters:

preambleField1 - first byte of the field specifying the format, often not transmitted in data interfaces, as it is constant for a given data interface

preambleField2 - second byte of the field specifying the format (added in revision 4 of the CCSDS standard in 2010), often not transmitted in data interfaces, as it is constant for a given data interface (value ignored if presence not signaled in preambleField1)

timeField - byte array containing the time code

agencyDefinedEpoch - reference epoch, ignored if the preamble field specifies the CCSDS reference epoch is used (and hence may be null in this case)

Returns:

an instance corresponding to the specified date

See Also:

parseCCSDSUnsegmentedTimeCode(byte, byte, byte[], AbsoluteDate, AbsoluteDate)

parseCCSDSUnsegmentedTimeCode

public static AbsoluteDate parseCCSDSUnsegmentedTimeCode(byte preambleField1,
                                                         byte preambleField2,
                                                         byte[] timeField,
                                                         AbsoluteDate agencyDefinedEpoch,
                                                         AbsoluteDate ccsdsEpoch)

Build an instance from a CCSDS Unsegmented Time Code (CUC).

CCSDS Unsegmented Time Code is defined in the blue book: CCSDS Time Code Format (CCSDS 301.0-B-4) published in November 2010

If the date to be parsed is formatted using version 3 of the standard (CCSDS 301.0-B-3 published in 2002) or if the extension of the preamble field introduced in version 4 of the standard is not used, then the preambleField2 parameter can be set to 0.

Parameters:

preambleField1 - first byte of the field specifying the format, often not transmitted in data interfaces, as it is constant for a given data interface

preambleField2 - second byte of the field specifying the format (added in revision 4 of the CCSDS standard in 2010), often not transmitted in data interfaces, as it is constant for a given data interface (value ignored if presence not signaled in preambleField1)

timeField - byte array containing the time code

agencyDefinedEpoch - reference epoch, ignored if the preamble field specifies the CCSDS reference epoch is used (and hence may be null in this case)

ccsdsEpoch - reference epoch, ignored if the preamble field specifies the agency epoch is used.

Returns:

an instance corresponding to the specified date

Since:

10.1

parseCCSDSDaySegmentedTimeCode

@DefaultDataContext
public static AbsoluteDate parseCCSDSDaySegmentedTimeCode(byte preambleField,
                                                                              byte[] timeField,
                                                                              DateComponents agencyDefinedEpoch)

Build an instance from a CCSDS Day Segmented Time Code (CDS).

CCSDS Day Segmented Time Code is defined in the blue book: CCSDS Time Code Format (CCSDS 301.0-B-4) published in November 2010

This method uses the default data context.

Parameters:

preambleField - field specifying the format, often not transmitted in data interfaces, as it is constant for a given data interface

timeField - byte array containing the time code

agencyDefinedEpoch - reference epoch, ignored if the preamble field specifies the CCSDS reference epoch is used (and hence may be null in this case)

Returns:

an instance corresponding to the specified date

See Also:

parseCCSDSDaySegmentedTimeCode(byte, byte[], DateComponents, TimeScale)

parseCCSDSDaySegmentedTimeCode

public static AbsoluteDate parseCCSDSDaySegmentedTimeCode(byte preambleField,
                                                          byte[] timeField,
                                                          DateComponents agencyDefinedEpoch,
                                                          TimeScale utc)

Build an instance from a CCSDS Day Segmented Time Code (CDS).

CCSDS Day Segmented Time Code is defined in the blue book: CCSDS Time Code Format (CCSDS 301.0-B-4) published in November 2010

Parameters:

preambleField - field specifying the format, often not transmitted in data interfaces, as it is constant for a given data interface

timeField - byte array containing the time code

agencyDefinedEpoch - reference epoch, ignored if the preamble field specifies the CCSDS reference epoch is used (and hence may be null in this case)

utc - time scale used to compute date and time components.

Returns:

an instance corresponding to the specified date

Since:

10.1

parseCCSDSCalendarSegmentedTimeCode

@DefaultDataContext
public static AbsoluteDate parseCCSDSCalendarSegmentedTimeCode(byte preambleField,
                                                                                   byte[] timeField)

Build an instance from a CCSDS Calendar Segmented Time Code (CCS).

CCSDS Calendar Segmented Time Code is defined in the blue book: CCSDS Time Code Format (CCSDS 301.0-B-4) published in November 2010

This method uses the default data context.

Parameters:

preambleField - field specifying the format, often not transmitted in data interfaces, as it is constant for a given data interface

timeField - byte array containing the time code

Returns:

an instance corresponding to the specified date

See Also:

parseCCSDSCalendarSegmentedTimeCode(byte, byte[], TimeScale)

parseCCSDSCalendarSegmentedTimeCode

public static AbsoluteDate parseCCSDSCalendarSegmentedTimeCode(byte preambleField,
                                                               byte[] timeField,
                                                               TimeScale utc)

Build an instance from a CCSDS Calendar Segmented Time Code (CCS).

CCSDS Calendar Segmented Time Code is defined in the blue book: CCSDS Time Code Format (CCSDS 301.0-B-4) published in November 2010

Parameters:

preambleField - field specifying the format, often not transmitted in data interfaces, as it is constant for a given data interface

timeField - byte array containing the time code

utc - time scale used to compute date and time components.

Returns:

an instance corresponding to the specified date

Since:

10.1

createJDDate

public static AbsoluteDate createJDDate(int jd,
                                        double secondsSinceNoon,
                                        TimeScale timeScale)

Build an instance corresponding to a Julian Day date.

Parameters:

jd - Julian day

secondsSinceNoon - seconds in the Julian day (BEWARE, Julian days start at noon, so 0.0 is noon)

timeScale - time scale in which the seconds in day are defined

Returns:

a new instant

createMJDDate

public static AbsoluteDate createMJDDate(int mjd,
                                         double secondsInDay,
                                         TimeScale timeScale)
                                  throws OrekitIllegalArgumentException

Build an instance corresponding to a Modified Julian Day date.

Parameters:

mjd - modified Julian day

secondsInDay - seconds in the day

timeScale - time scale in which the seconds in day are defined

Returns:

a new instant

Throws:

OrekitIllegalArgumentException - if seconds number is out of range

createJulianEpoch

@DefaultDataContext
public static AbsoluteDate createJulianEpoch(double julianEpoch)

Build an instance corresponding to a Julian Epoch (JE).

According to Lieske paper: Precession Matrix Based on IAU (1976) System of Astronomical Constants, Astronomy and Astrophysics, vol. 73, no. 3, Mar. 1979, p. 282-284, Julian Epoch is related to Julian Ephemeris Date as:

 JE = 2000.0 + (JED - 2451545.0) / 365.25
 

This method reverts the formula above and computes an AbsoluteDate from the Julian Epoch.

This method uses the default data context.

Parameters:

julianEpoch - Julian epoch, like 2000.0 for defining the classical reference J2000.0

Returns:

a new instant

See Also:

J2000_EPOCH, createBesselianEpoch(double), TimeScales.createJulianEpoch(double)

createBesselianEpoch

@DefaultDataContext
public static AbsoluteDate createBesselianEpoch(double besselianEpoch)

Build an instance corresponding to a Besselian Epoch (BE).

According to Lieske paper: Precession Matrix Based on IAU (1976) System of Astronomical Constants, Astronomy and Astrophysics, vol. 73, no. 3, Mar. 1979, p. 282-284, Besselian Epoch is related to Julian Ephemeris Date as:

 BE = 1900.0 + (JED - 2415020.31352) / 365.242198781
 

This method reverts the formula above and computes an AbsoluteDate from the Besselian Epoch.

This method uses the default data context.

Parameters:

besselianEpoch - Besselian epoch, like 1950 for defining the classical reference B1950.0

Returns:

a new instant

See Also:

createJulianEpoch(double), TimeScales.createBesselianEpoch(double)

shiftedBy

public AbsoluteDate shiftedBy(double dt)

Get a time-shifted date.

Calling this method is equivalent to call new AbsoluteDate(this, dt).

Specified by:

shiftedBy in interface TimeShiftable<AbsoluteDate>

Parameters:

dt - time shift in seconds

Returns:

a new date, shifted with respect to instance (which is immutable)

See Also:

PVCoordinates.shiftedBy(double), Attitude.shiftedBy(double), Orbit.shiftedBy(double), SpacecraftState.shiftedBy(double)

durationFrom

public double durationFrom(AbsoluteDate instant)

Compute the physically elapsed duration between two instants.

The returned duration is the number of seconds physically elapsed between the two instants, measured in a regular time scale with respect to surface of the Earth (i.e either the TAI scale, the TT scale or the GPS scale). It is the only method that gives a duration with a physical meaning.

This method gives the same result (with less computation) as calling offsetFrom(AbsoluteDate, TimeScale) with a second argument set to one of the regular scales cited above.

This method is the reverse of the AbsoluteDate(AbsoluteDate, double) constructor.

Parameters:

instant - instant to subtract from the instance

Returns:

offset in seconds between the two instants (positive if the instance is posterior to the argument)

See Also:

offsetFrom(AbsoluteDate, TimeScale), AbsoluteDate(AbsoluteDate, double)

offsetFrom

public double offsetFrom(AbsoluteDate instant,
                         TimeScale timeScale)

Compute the apparent clock offset between two instant in the perspective of a specific time scale.

The offset is the number of seconds counted in the given time scale between the locations of the two instants, with all time scale irregularities removed (i.e. considering all days are exactly 86400 seconds long). This method will give a result that may not have a physical meaning if the time scale is irregular. For example since a leap second was introduced at the end of 2005, the apparent offset between 2005-12-31T23:59:59 and 2006-01-01T00:00:00 is 1 second, but the physical duration of the corresponding time interval as returned by the durationFrom(AbsoluteDate) method is 2 seconds.

This method is the reverse of the AbsoluteDate(AbsoluteDate, double, TimeScale) constructor.

Parameters:

instant - instant to subtract from the instance

timeScale - time scale with respect to which the offset should be computed

Returns:

apparent clock offset in seconds between the two instants (positive if the instance is posterior to the argument)

See Also:

durationFrom(AbsoluteDate), AbsoluteDate(AbsoluteDate, double, TimeScale)

timeScalesOffset

public double timeScalesOffset(TimeScale scale1,
                               TimeScale scale2)

Compute the offset between two time scales at the current instant.

The offset is defined as l₁-l₂ where l₁ is the location of the instant in the scale1 time scale and l₂ is the location of the instant in the scale2 time scale.

Parameters:

scale1 - first time scale

scale2 - second time scale

Returns:

offset in seconds between the two time scales at the current instant

toDate

public Date toDate(TimeScale timeScale)

Convert the instance to a Java Date.

Conversion to the Date class induces a loss of precision because the Date class does not provide sub-millisecond information. Java Dates are considered to be locations in some times scales.

Parameters:

timeScale - time scale to use

Returns:

a Date instance representing the location of the instant in the time scale

getComponents

public DateTimeComponents getComponents(TimeScale timeScale)

Split the instance into date/time components.

Parameters:

timeScale - time scale to use

Returns:

date/time components

getComponents

@DefaultDataContext
public DateTimeComponents getComponents(int minutesFromUTC)

Split the instance into date/time components for a local time.

This method uses the default data context.

Parameters:

minutesFromUTC - offset in minutes from UTC (positive Eastwards UTC, negative Westward UTC)

Returns:

date/time components

Since:

7.2

See Also:

getComponents(int, TimeScale)

getComponents

public DateTimeComponents getComponents(int minutesFromUTC,
                                        TimeScale utc)

Split the instance into date/time components for a local time.

Parameters:

minutesFromUTC - offset in minutes from UTC (positive Eastwards UTC, negative Westward UTC)

utc - time scale used to compute date and time components.

Returns:

date/time components

Since:

10.1

getComponents

@DefaultDataContext
public DateTimeComponents getComponents(TimeZone timeZone)

Split the instance into date/time components for a time zone.

This method uses the default data context.

Parameters:

timeZone - time zone

Returns:

date/time components

Since:

7.2

See Also:

getComponents(TimeZone, TimeScale)

getComponents

public DateTimeComponents getComponents(TimeZone timeZone,
                                        TimeScale utc)

Split the instance into date/time components for a time zone.

Parameters:

timeZone - time zone

utc - time scale used to computed date and time components.

Returns:

date/time components

Since:

10.1

compareTo

public int compareTo(AbsoluteDate date)

Compare the instance with another date.

Specified by:

compareTo in interface Comparable<AbsoluteDate>

Parameters:

date - other date to compare the instance to

Returns:

a negative integer, zero, or a positive integer as this date is before, simultaneous, or after the specified date.

getDate

public AbsoluteDate getDate()

Get the date.

Specified by:

getDate in interface TimeStamped

Returns:

date attached to the object

equals

public boolean equals(Object date)

Check if the instance represents the same time as another instance.

Overrides:

equals in class Object

Parameters:

date - other date

Returns:

true if the instance and the other date refer to the same instant

isEqualTo

public boolean isEqualTo(TimeStamped other)

Check if the instance represents the same time as another.

Parameters:

other - the instant to compare this date to

Returns:

true if the instance and the argument refer to the same instant

Since:

10.1

See Also:

isCloseTo(TimeStamped, double)

isCloseTo

public boolean isCloseTo(TimeStamped other,
                         double tolerance)

Check if the instance time is close to another.

Parameters:

other - the instant to compare this date to

tolerance - the separation, in seconds, under which the two instants will be considered close to each other

Returns:

true if the duration between the instance and the argument is strictly below the tolerance

Since:

10.1

See Also:

isEqualTo(TimeStamped)

isBefore

public boolean isBefore(TimeStamped other)

Check if the instance represents a time that is strictly before another.

Parameters:

other - the instant to compare this date to

Returns:

true if the instance is strictly before the argument when ordering chronologically

Since:

10.1

See Also:

isBeforeOrEqualTo(TimeStamped)

isAfter

public boolean isAfter(TimeStamped other)

Check if the instance represents a time that is strictly after another.

Parameters:

other - the instant to compare this date to

Returns:

true if the instance is strictly after the argument when ordering chronologically

Since:

10.1

See Also:

isAfterOrEqualTo(TimeStamped)

isBeforeOrEqualTo

public boolean isBeforeOrEqualTo(TimeStamped other)

Check if the instance represents a time that is before or equal to another.

Parameters:

other - the instant to compare this date to

Returns:

true if the instance is before (or equal to) the argument when ordering chronologically

Since:

10.1

See Also:

isBefore(TimeStamped)

isAfterOrEqualTo

public boolean isAfterOrEqualTo(TimeStamped other)

Check if the instance represents a time that is after or equal to another.

Parameters:

other - the instant to compare this date to

Returns:

true if the instance is after (or equal to) the argument when ordering chronologically

Since:

10.1

See Also:

isAfterOrEqualTo(TimeStamped)

isBetween

public boolean isBetween(TimeStamped boundary,
                         TimeStamped otherBoundary)

Check if the instance represents a time that is strictly between two others representing the boundaries of a time span. The two boundaries can be provided in any order: in other words, whether boundary represents a time that is before or after otherBoundary will not change the result of this method.

Parameters:

boundary - one end of the time span

otherBoundary - the other end of the time span

Returns:

true if the instance is strictly between the two arguments when ordering chronologically

Since:

10.1

See Also:

isBetweenOrEqualTo(TimeStamped, TimeStamped)

isBetweenOrEqualTo

public boolean isBetweenOrEqualTo(TimeStamped boundary,
                                  TimeStamped otherBoundary)

Check if the instance represents a time that is between two others representing the boundaries of a time span, or equal to one of them. The two boundaries can be provided in any order: in other words, whether boundary represents a time that is before or after otherBoundary will not change the result of this method.

Parameters:

boundary - one end of the time span

otherBoundary - the other end of the time span

Returns:

true if the instance is between the two arguments (or equal to at least one of them) when ordering chronologically

Since:

10.1

See Also:

isBetween(TimeStamped, TimeStamped)

hashCode

public int hashCode()

Get a hashcode for this date.

Overrides:

hashCode in class Object

Returns:

hashcode

toString

@DefaultDataContext
public String toString()

Get a String representation of the instant location in UTC time scale.

This method uses the default data context.

Overrides:

toString in class Object

Returns:

a string representation of the instance, in ISO-8601 format with milliseconds accuracy

See Also:

toString(TimeScale)

toString

public String toString(TimeScale timeScale)

Get a String representation of the instant location.

Parameters:

timeScale - time scale to use

Returns:

a string representation of the instance, in ISO-8601 format with milliseconds accuracy

toString

@DefaultDataContext
public String toString(int minutesFromUTC)

Get a String representation of the instant location for a local time.

This method uses the default data context.

Parameters:

minutesFromUTC - offset in minutes from UTC (positive Eastwards UTC, negative Westward UTC).

Returns:

string representation of the instance, in ISO-8601 format with milliseconds accuracy

Since:

7.2

See Also:

toString(int, TimeScale)

toString

public String toString(int minutesFromUTC,
                       TimeScale utc)

Get a String representation of the instant location for a local time.

Parameters:

minutesFromUTC - offset in minutes from UTC (positive Eastwards UTC, negative Westward UTC).

utc - time scale used to compute date and time components.

Returns:

string representation of the instance, in ISO-8601 format with milliseconds accuracy

Since:

10.1

toString

@DefaultDataContext
public String toString(TimeZone timeZone)

Get a String representation of the instant location for a time zone.

This method uses the default data context.

Parameters:

timeZone - time zone

Returns:

string representation of the instance, in ISO-8601 format with milliseconds accuracy

Since:

7.2

See Also:

toString(TimeZone, TimeScale)

toString

public String toString(TimeZone timeZone,
                       TimeScale utc)

Get a String representation of the instant location for a time zone.

Parameters:

timeZone - time zone

utc - time scale used to compute date and time components.

Returns:

string representation of the instance, in ISO-8601 format with milliseconds accuracy

Since:

10.1

toStringRfc3339

public String toStringRfc3339(TimeScale utc)

Represent the given date as a string according to the format in RFC 3339. RFC3339 is a restricted subset of ISO 8601 with a well defined grammar.

This method is different than toString(TimeScale) in that it includes a "Z" at the end to indicate the time zone and enough precision to represent the point in time without rounding up to the next minute.

RFC3339 is unable to represent BC years, years of 10000 or more, time zone offsets of 100 hours or more, or NaN. In these cases the value returned from this method will not be valid RFC3339 format.

Parameters:

utc - time scale.

Returns:

RFC 3339 format string.

See Also:

RFC 3339, DateTimeComponents.toStringRfc3339(), toString(TimeScale), getComponents(TimeScale)