Package org.orekit.time

This independent package provides classes to handle epochs, time scales, and to compare instants together.

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:

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:

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.

Author:
L. Maisonobe
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