Kozai::TLE::Elements
A parsed two-line element set.
Angles are in degrees and mean motion in revolutions per day, exactly as
they appear in the file. SGP4 converts to radians and radians per minute
at initialisation; keeping the raw units here means a round trip through
this struct changes nothing.
This is a struct: element sets are created once per satellite and copied
freely into propagator state, and there is no reason to put them on the
heap.
Constructors
Instance methods
How old these elements are at at.
Accuracy degrades as this grows; the API reports it on every response and the web interface warns on it, because a plausible-looking answer from a week-old element set is the most common way to be wrong here.
Whether the deep-space branch of the model applies.
NOTE: the model switches to SDP4 at a period of 225 minutes, per Spacetrack Report No. 3. Below roughly 6.4 revolutions per day the near-earth branch is not merely less accurate, it is wrong — lunar and solar perturbations and resonance effects are simply absent from it.
Epoch as a UTC Time.
Precision is limited to nanoseconds by Time. For propagation use
#epoch_year and #epoch_day directly, or Timescale.julian_date,
which keep the full Float64 day fraction.
International designator (launch year, launch number, piece), or nil
when the field is blank — which happens in older and synthetic sets.
Mean motion in revolutions per day.
This is the Kozai mean motion; SGP4 converts it to the Brouwer
definition during initialisation.
Second derivative of mean motion divided by six, in revolutions per day cubed, as stored in the file.
First derivative of mean motion divided by two, in revolutions per day squared, as stored in the file.
Unused by SGP4 itself, which derives drag from #bstar; retained because
it is part of the element set and appears in the API.