Greg Roberts wrote: > (2) #91080 is a very interesting unknown as it was flying formation > with #21798. I had a second pass and the unknown was still in the > same position relative to #21798 so the orbits must be very similar. > I have no match in my element database. The unknown was variable > but easy for 90% of the pass. #21798 produced some very bright flashes. > The second pass was difficult as the elevation was 11 degrees. Nice catch, Greg! I confirm the apparent formation: the unknown companion of DMSP B5D2-6 (91082A / 21798) preceded it by about 1.09 s on both passes. Based on the orbital velocity of the DMSP, the companion was leading by about 8.0 km. I suspect the companion may be XSS-11 (28636 / 05011A). Greg, on 2006 Jul 18 UTC, you were the last to observe both, which resulted in the most recent hobbyist elements: DMSP B5D2-6 6.4 1.7 0.0 6.6 v 5.43 1 21798U 91082A 06199.68681329 .00000050 00000-0 25530-4 0 02 2 21798 98.6393 208.9319 0012500 163.2370 196.7629 14.15652861 08 XSS-11 1.0 0.6 0.0 7.9 v 1.20 1 28636U 05011A 06199.66503589 .00000120 00000-0 39812-4 0 02 2 28636 99.1780 206.5354 0012000 341.9670 18.0329 14.37843992 02 At that time, XSS-11's plane was about 2.4 deg west (206.5354 - 208.9319) of the DMSP, but its rate of eastward precession was about 0.097 deg/d greater than that of the DMSP, so they should have become coplanar late on Aug 11 UTC, which would have been the date of the rendezvous. Let's see what is revealed by further observations. Ted Molczan ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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