Lutz Schindler,lschindler@assi.s-link.de asked me about how to observe decaying satellites: Hello Lutz, thanks for your inquiry! I have no ready-made answer, I guess it will depend on what you want to do, what you you want out of it for yourself, what you want to contribute, and if you want to observe and/or compute. Also, which prediction program(s) you use, and if you are willing to use more programs. As for observing, my tips are: 1. Inspect your elsets to know well in advance which objects have old, inaccurate elsets, and which are about to decay. 2. Observe the decay candidates while their elsets are reliable, so that you know their magnitude and flashing patterns. 3. Use NASA GSFC OIG RBBS (!) to get recent elsets for decay candidates, if not sufficiently new are obtained here or other places. 4. When decay closes in (and/or weekends stop the flow of elsets) make notes of which elset you used for prediction, and how many seconds before/after prediction your observation is. Use this for extrapolation, to make it easier to find the last days. The effect of elset errors is usually quadratic with respect to age of elset, perhaps ndot2 * (day-Epoch)**2 * 2000 seconds, and the expected decay day = Epoch + 0.08 / ndot2 or later. Near the decay, the inaccuracy grows faster - I use time * ln(time) , where time=remaining life time, as a factor. If you don't know how to find the components of the equations, let me know, and/or look in a previous mail I wrote July 28 ! ============================================================ == bjorn.gimle@online.dextel.se ; 59.22371 N, 18.22857 E == ==(Bjorn_gimle@lector.kth.se)==(bjorn.gimle@duesenberg.se)== ============================================================ ************ Sent via DN Online (Sweden) UUCP Gateway **************