I've been following with interest the postings regarding the coming decay of Cosmos 2264 (USSPACECOM #22808). Of particular interest are the comments about "ndot2" values. What exactly are these values? Are they present in the TLE listing (i.e. are they the drag term)? Or is it a derived value from info contained within the TLE? In any case, I would be interested in a brief explanation how one uses a ndot2 value along with other parms to deduce a probable re-entry date. And what are "exceptional" values. I understand that to some of the more experienced observers out there, there may be something akin to a "gut feel" about these values. But we all have to start somewhere :-) Thanks in advance.....Bill ______________________________________________________________________ < krosney@cc.umanitoba.ca | > < Bill Krosney | > ----------------------------------------------------------------------