imap_processing.spice.time.ttj2000ns_to_et#
- imap_processing.spice.time.ttj2000ns_to_et(tt_ns: _Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | bool | int | float | complex | str | bytes | _NestedSequence[bool | int | float | complex | str | bytes]) ndarray[tuple[int, ...], dtype[float]]#
Convert TT J2000 epoch nanoseconds to TDB J2000 epoch seconds.
The common CDF coordinate epoch stores terrestrial time (TT) J2000 nanoseconds. SPICE requires Barycentric Dynamical Time (TDB, aka ET) J2000 floating point seconds for most geometry related functions. This is a common function to do that conversion.
- Parameters:
tt_ns (float, numpy.ndarray) – Number of nanoseconds since the J2000 epoch in the TT timescale.
- Returns:
Number of seconds since the J2000 epoch in the TDB timescale.
- Return type: