toEcf method
Converts this ECI object to ECF.
Implementation
EarthCenteredEarthFixed toEcf(Angle gmst) {
final s = sin(gmst.radians);
final c = cos(gmst.radians);
final x = this.x * c + this.y * s;
final y = this.x * (-s) + this.y * c;
return EarthCenteredEarthFixed(x, y, z);
}