Walter Nissen wrote: >With objects deep in the atmosphere >like this, the accuracy of elsets can degenerate horribly outside of a >narrow window. You don't say what you mean by a few minutes, but that >might not be enough. >Using only the elset closest to the desired pass, the one with epoch >96231, I see only one "predicted" pass: > > 38.458 121.398 31. Varney, CA <--------- 1950 13.5 4 F F F F F > >*** 1996 Aug 18 *** Times are UT *** 345 1231 > > H M S TIM AL AZI C U MAG REVS HGT SHD RNG EW PHS R A DEC >23797 Raduga 33 SL-1 >11 19 36 1.6 13 180 162 24.0 6.2 1584 54 3528 .5 48 058 -38.8 > >and none of this "activity" appears to occur around the time you looked. Thanks for looking into this. I use Quicksat to generate an evening's worth of predictions. For objects such as this that are in unstable orbits, I usually rely on Trakstar because it is a "pure" implementation of SGP4. [Not to imply Quicksat isn't pure. I don't know what routines are in Quicksat, but I do know what is in Trakstar because Dr. Kelso provides the source code.] Using the elset Raduga 33 R/B(D) 1 23797U 96010D 96229.05467116 +.26361494 +17384-4 +13165-2 0 02771 2 23797 047.8010 213.6600 2868208 063.1898 323.7229 10.02738645004926 Trakstar gives 1996 Aug 18 03:24:50 SAC 281.5746 31.6074 208.127 -5.337090 1996 Aug 18 03:25:00 SAC 307.3956 39.8688 167.616 -2.526458 1996 Aug 18 03:25:10 SAC 345.7169 40.1518 162.841 1.625028 1996 Aug 18 03:25:20 SAC 14.0625 31.1912 196.461 4.852553 which led me to go out and take a chance on seeing it. Alan Pickup's TLE Raduga 33 R/B(D) 1 23797U 96010D 96230.02026870 .34378235 20746-1 10964-2 0 92774 2 23797 47.7595 211.3063 2580813 65.3926 319.2471 10.65791595 5023 with Trakstar gives these not very good choices (near culmination) 1996 Aug 18 02:46:20 SAC 149.7443 20.1500 372.418 -1.050338 1996 Aug 18 04:57:30 SAC 352.3775 3.0607 882.755 0.951147 So, yes, these rapidly changing elsets do generate disparate results. But I don't know if both elsets are correct, one or the other are correct, or neither. Better to go out for ten minutes on the chance of seeing it rather than miss it due to a decision to not go out because of a perception that the prediction is spurious. That said, my report of not seeing Raduga 33 r/b(D) can either be taken as a "true negative" or a "false negative" depending on your faith in the 229 elset. Now the question that goes begging is: why did Trakstar generate a pass for 0325 UT while Quicksat did not? My hunch is that it has to do with the fact that Quicksat ignores B* while Trakstar does not. Would like your thoughts or anyone else's on this. -- Jim "Celestial mechanics is entitled to be regarded as the most perfect science" Forest Ray Moulton