See: Description
Interface | Description |
---|---|
FieldTimeInterpolable<T extends FieldTimeInterpolable<T,KK>,KK extends org.hipparchus.RealFieldElement<KK>> |
This interface represents objects that can be interpolated in time.
|
FieldTimeShiftable<T extends FieldTimeInterpolable<T,KK>,KK extends org.hipparchus.RealFieldElement<KK>> |
This interface represents objects that can be shifted in time.
|
FieldTimeStamped<T extends org.hipparchus.RealFieldElement<T>> |
This interface represents objects that have a
AbsoluteDate
date attached to them. |
TimeInterpolable<T extends TimeInterpolable<T>> |
This interface represents objects that can be interpolated in time.
|
TimeScalarFunction |
This interface represents a scalar function of time.
|
TimeScale |
Interface for time scales.
|
TimeShiftable<T extends TimeShiftable<T>> |
This interface represents objects that can be shifted in time.
|
TimeStamped |
This interface represents objects that have a
AbsoluteDate
date attached to them. |
TimeVectorFunction |
This interface represents a multi-valued function of time.
|
UTCTAIOffsetsLoader |
Interface for loading UTC-TAI offsets data files.
|
Class | Description |
---|---|
AbsoluteDate |
This class represents a specific instant in time.
|
ChronologicalComparator |
Comparator for
TimeStamped instance. |
DateComponents |
Class representing a date broken up as year, month and day components.
|
DateTimeComponents |
Holder for date and time components.
|
FieldAbsoluteDate<T extends org.hipparchus.RealFieldElement<T>> |
This class represents a specific instant in time.
|
GalileoScale |
Galileo system time scale.
|
GLONASSScale |
GLONASS time scale.
|
GMSTScale |
Greenwich Mean Sidereal Time.
|
GPSScale |
GPS time scale.
|
OffsetModel |
TAI UTC offset model.
|
QZSSScale |
QZSS time scale.
|
TAIScale |
International Atomic Time.
|
TAIUTCDatFilesLoader |
Loader for UTC-TAI extracted from tai-utc.dat file from USNO.
|
TCBScale |
Barycentric Coordinate Time.
|
TCGScale |
Geocentric Coordinate Time.
|
TDBScale |
Barycentric Dynamic Time.
|
TimeComponents |
Class representing a time within the day broken up as hour,
minute and second components.
|
TimeScalesFactory |
Factory for predefined time scales.
|
TTScale |
Terrestrial Time as defined by IAU(1991) recommendation IV.
|
UT1Scale |
Universal Time 1.
|
UTCScale |
Coordinated Universal Time.
|
UTCTAIBulletinAFilesLoader |
Loader for UTC-TAI extracted from bulletin A files.
|
UTCTAIHistoryFilesLoader |
Loader for UTC versus TAI history files.
|
Enum | Description |
---|---|
Month |
Enumerate representing a calendar month.
|
The principal class is AbsoluteDate
which represents a unique instant in time, with no ambiguity. For that
purpose, the ways to define this object are quite strict.
The easiest and most evident way is to define an instant with an offset from another one. Orekit defines 9 reference epochs. The first 6 are commonly used in the space community, the seventh one is commonly used in the computer science field and the last two are convenient for initialization in min/max research loops:
Julian Epoch
: -4712-01-01 at 12:00:00, TTScaleModified Julian Epoch
: 1858-11-17 at 00:00:00, TTScaleFifties Epoch
: 1950-01-01 at 00:00:00, TTScaleCCSDS Epoch
: 1958-01-01 at 00:00:00, TAIScaleGPS Epoch
: 1980-01-06 at 00:00:00, UTCScaleJ2000 Epoch
: 2000-01-01 at 12:00:00, TTScaleJava Epoch
: 1970-01-01 at 00:00:00, TTScalePast infinity
: at infinity in the past,Future infinity
: at infinity in the future.The second definition, which could be the source of some confusion if not used with care, is by giving a location (a date) in a specific time scale. It is of prime importance to understand the various available time scales definitions to avoid mistakes. Orekit provides 9 of the most important ones:
TAIScale
: International Atomic Time,TTScale
: Terrestrial Time as defined by IAU(1991)
recommendation IV.
Coordinate time at the surface of the Earth. It is the successor of
Ephemeris Time TE. By convention, TT = TAI + 32.184 s,UTCScale
: Coordinated Universal Time.
UTC is related to TAI using step adjustments from time to time according
to IERS (International Earth Rotation Service) rules. These adjustments
require introduction of leap seconds.
Some leaps are already known and predefined in the library (at least
from 1972-01-01 to 2009-01-01) and other ones can be supported by
providing UTC-TAI.history files using the data loading mechanism
provided by DataProvidersManager
,UT1Scale
: Universal Time 1.
UT1 is a time scale directly linked to the actual rotation of the Earth.
It is an irregular scale, reflecting Earth irregular rotation rate.
The offset between UT1 and UTCScale
is found in
the Earth Orientation Parameters published by IERS,TCGScale
: Geocentric Coordinate Time.
Coordinate time at the center of mass of the Earth.
This time scale depends linearly on TTScale,TDBScale
: Barycentric Dynamic Time.
Time used to compute ephemerides in the solar system.
This time is offset with respect to TT by small relativistic corrections
due to Earth motion,TCBScale
: Barycentric Coordinate Time.
Coordinate time used for computations in the solar system.
This time scale depends linearly on TDBScale,GPSScale
: Global Positioning System reference scale.
This scale was equal to UTC at start of the GPS Epoch
when it was 19 seconds
behind TAI, and remained parallel to TAI since then (i.e. UTC is now
offset from GPS due to leap seconds). TGPS = TAI - 19 s,GMSTScale
: Greenwich Mean Sidereal Time scale.
The Greenwich Mean Sidereal Time is the hour angle between the meridian
of Greenwich and mean equinox of date at 0h UT1.
Once it is built, an AbsoluteDate
can be compared to
other ones, and expressed in other time scales. It is used to define states,
orbits, frames... Classes that include a date implement the TimeStamped
interface.
The ChronologicalComparator
singleton can sort objects
implementing this interface chronologically.
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