imap_processing.spice.time.met_to_ttj2000ns#
- imap_processing.spice.time.met_to_ttj2000ns(met: _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[int64]]#
Convert mission elapsed time (MET) to terrestrial time nanoseconds since J2000.
- Parameters:
met (float, numpy.ndarray) – Number of seconds since epoch according to the spacecraft clock.
- Returns:
The mission elapsed time converted to nanoseconds since the J2000 epoch in the terrestrial time (TT) timescale.
- Return type:
numpy.ndarray[numpy.int64]
Notes
There are two options when using SPICE to convert from SCLK time (MET) to J2000. The conversion can be done on SCLK strings as input or using double precision continuous spacecraft clock “ticks”. The latter is more accurate as it will correctly convert fractional clock ticks to nanoseconds. Since some IMAP instruments contain clocks with higher precision than 1 SCLK “tick” which is defined to be 20 microseconds, according to the sclk kernel, it is preferable to use the higher accuracy method.