Ted's 3.56 s period diff relates to these elset, but IGS' is 7 days old. We have agreed to use average elsets for the IGS satellites, because they are frequently adjusted and remain within +-10 s of a no-drag elset. However, it seems Mike is using current MeanMotion at Epoch time. Drag is about .0001, so if no reboost in the interim MM should be around 15.2611, the period diff 4.1 and the near collision one rev. later. Also, it would have been 6 s early at the time of Ted's obs, but in reality it was just .5 s early, so I believe there WAS a reboost in-between, in which case the period should be reasonably correct at the time of observation. Correcting just the .5 s diff, ALLCOLA gives a close approach of 5.1 km at 14:25, where the vertical separation is 4.0 km. Where the orbits are closer (2.6 km) the distance has increased. Using Scott's elset I get 12:54:29.24 27699 IGS 1B 8.5/ 5.0 and later a smaller vertical separation, but larger horisontal. ----- Original Message ----- .. > As Russell Eberst mentioned, 02049A is close to 03009B. I observed it is a > stray, preceding 03009B by 27 s, on nearly the identical path. > > Their orbital planes are about 0.1 deg apart, and their inclinations are almost > identical. 03009B is 2.9 km lower than 02049A, so its period is shorter - by > about 3.56 s; therefore, it should overtake it about 7.5 revs after my > observation, or about 14:21 UTC today (May 20) - assuming neither one perform a > reboost manoeuvre in the interim. > > Zi Yuan-2B 0.0 0.0 0.0 5.6 v > 1 27550U 02049A 04140.86597222 .00003393 00000-0 13874-3 0 8942 > 2 27550 97.3366 213.4334 0004640 11.1348 159.5813 15.25020219 86976 > > IGS 1B 0.0 0.0 0.0 3.3 v > 1 27699U 03009B 04134.14681067 .00000000 00000-0 00000-0 0 03 > 2 27699 97.3730 206.9008 0002000 34.7558 325.2441 15.25979348 07 > > Description of 2-line elements (above): http://www.satobs.org/element.html ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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