Kevin Fetter wrote: > Here's a orbit for lacrosse 1 > > at/Z97 > 1 19671U 97103.13464606 .00003800 56900-5 38 > 2 19671 56.9763 336.1234 0372855 247.0528 112.5202 15.51176045 5431 > > It was found at > > http://www.planet4589.org/space/elements/19600/S19671 That elset was not of Lacrosse 1, so it should not be in the above compilation. Here is how it came to exist: Lacrosse 1 was last observed (by Russell Eberst), on 1997 Mar 24 UTC. At first it was uncertain whether it had been manoeuvred to a new orbit, or removed from orbit, so hobbyists attempted to find it, and generally kept an eye out for it. That resulted in this report of an unknown magnitude 3 object (about the same brightness as Lacrosse), observed on 1997 Apr 11 UTC: http://satobs.org/seesat/Apr-1997/0098.html which was identified as Aureole 1 r (5730 / 71119B), as reported here: http://satobs.org/seesat/Apr-1997/0111.html There was lingering doubt that the mag 3 object was 71119B, because it was brighter than 71119B was predicted to be. I do not know what standard magnitude was used in the prediction, but the correct value is 4.9 (1000 km, 90 deg phase), which predicts magnitude 3 for the circumstances of the observation, per this elset: Aureole 1 r 7.4 2.4 0.0 4.9 v 10.0 1 05730U 71119B 97101.13267896 .00001619 00000-0 14697-3 0 464 2 05730 73.9180 334.0415 0978812 177.8540 182.7266 13.36200997194705 One additional doubt about Aureole 1 r, was that it was known to rotate, yet the Apr 11 object was steady in brightness; however, depending on the observer's location relative the spin-axis, it could have appeared steady, despite its rotation. Russell Eberst experienced exactly that, with this very object: 7111902 2420 19970215 045437.41 144845+514059 5.6 7.7 3.5 R 7111902 2420 19970215 045458.71 145856+472828 5.6 7.7 3.5 R 7111902 2420 19970218 185110.44 111007+552025 5.8 5.8 0 S 7111902 2420 19970320 231735.00 040157+652011 6.5 6.5 0 S 7111902 2420 19970608 233946.38 211152+093043 5.3 8.6 5.37 R On 1997 Feb 15, he observed a regular variation over a 3.5 s period, yet it was steady on Feb 18 and Mar 20. Then on Jun 08, it was varying again. So the Apr 11 object's match to Aureole 1 r is quite good, while any relationship to Lacrosse 1 was conjecture. The above bogus Lacrosse 1 elset was an estimate of the orbit it would have to have manoeuvred to after it disappeared, in order to fit the circumstances of the observation of the Apr 11 object, as discussed here: http://satobs.org/seesat/Apr-1997/0165.html Since the elset was purely hypothetical, it should not have been published with Lacrosse 1's catalogue number, but with a dummy value, like 99999. And it should not have been included in the compilation. The second-to-last elset in the compilation (epoch 97084.34433668), also is an estimate, as was discussed here: http://satobs.org/seesat/Apr-1997/0101.html It also should have been published with a dummy catalogue number, and it should not have been included in the compilation. We often need to create hypothetical or estimated elsets, but we should use dummy catalogue numbers and international designations, to avoid their being confused with elements derived from observations. I did not follow this rule at first, but adopted it when I found many of my old estimated elsets polluting the historical archives. Ted Molczan ----------------------------------------------------------------- To unsubscribe from SeeSat-L, send a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@satobs.org List archived at http://www.satobs.org/seesat/seesatindex.html
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