planetary function

({double deltaD, double t}) planetary(double t1, double t5, List<Equatorial> cs1, List<Equatorial> cs2,)

Computes a conjunction between two moving objects (e.g. planets).

Conjunction is found with interpolation against length-5 ephemerides. t1, t5 are times of first and last rows. cs1, cs2 are 5-row ephemerides as Equatorial coordinates.

Returns time of conjunction t and the amount deltaD that object 2 was "above" object 1 at the time of conjunction (in declination, radians).

Implementation

({double t, double deltaD}) planetary(
    double t1, double t5, List<Equatorial> cs1, List<Equatorial> cs2) {
  if (cs1.length != 5 || cs2.length != 5) {
    throw ArgumentError('Five rows required in ephemerides');
  }
  final dr = List<double>.generate(5, (i) => cs2[i].ra - cs1[i].ra);
  final dd = List<double>.generate(5, (i) => cs2[i].dec - cs1[i].dec);
  return _conj(t1, t5, dr, dd);
}