Can anybody check my approach here?<br><br>parameters:<br> omega = argument of periapsis (clockwise angle from line of ascending node to semi-major axis)<br> a = semi-major axis<br> e = eccentricity<br> ta = true anomaly (counter-clockwise angle from semi-major axis to object position on orbit)<br>
<br>- omega is provided in TLE (as argument of perigee)<br>- a is recovered by norad lib (cOrbit instance)<br>- e is provided in TLE<br><br>Assuming that the true anomaly of interest is on the line of the ascending node,<br>
ta = 360 - omega<br><br>Earth center is the primary focus of the orbit ellipse.<br><br>Radius from a focus to a point on the ellipse is given by<br> r = (a * (1 - e^2)) / (1 + (e * cos(ta)))<br><br>Critical region is 12289 >= r >= 13289<br>
<br>Applying this to Keith's 'interesting' TLE data yields no critical intersections.<br><br>Side note: norad lib appears to provide orbital distance from surface of Earth instead of<br>center in some cases. Perigees of sample TLEs are reported as in the range 200 - 5000 km.<br>
I'm adding mean Earth radius 6371km, but I'm not sure I have this right.<br><br>- tony<br><br><br><br><br><br><br><br><br><br><br>