**Previous message:**Ted Molczan: "X-37B uodated orbit"**In reply to:**Ted Molczan: "X-37B uodated orbit"**Next in thread:**Ted Molczan: "RE: X-37B updated orbit"**Reply:**Ted Molczan: "RE: X-37B updated orbit"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

Adding Brad Young's observations of this morning, to Greg Roberts' of Aug 19 UTC, results in a more accurate mean motion. The object was nearly 3 min late this morning, relative the preliminary elements I posted yesterday. The updated elements should be accurate to within about 10 s, per day since epoch. The following elements are based on the assumption that inclination and eccentricity were unaffected by the manoeuvre: OTV-1 430 X 447 km 1 36514U 10015A 10233.44511480 .00000000 00000-0 00000-0 0 05 2 36514 39.9851 336.7418 0012533 356.1476 3.9234 15.43353074 00 Arc 20100819.75-0821.46 WRMS resid 0.049 totl 0.024 xtrk I am fairly confident in the inclination, but in some doubt about the eccentricity. If the intent of the change in orbit was to raise the altitude, and to retain the original eccentricity, then there would have been two manoeuvres: one at perigee to raise the apogee, and one at apogee to raise the perigee; however, the data may be hinting at a single manoeuvre, at apogee, raising the perigee such that it became the new apogee: OTV-1 413 X 465 km 1 36514U 10015A 10233.44517289 .00000000 00000-0 00000-0 0 08 2 36514 39.9851 336.7626 0037995 3.5768 356.5305 15.43259984 08 Arc 20100819.75-0821.46 WRMS resid 0.026 totl 0.005 xtrk Brad's pass was nearly overhead, so he was within the plane of the orbit, which helped nail down the inclination and plane (RAAN), but was not ideal for resolving the eccentricity and argument of perigee. Barring any further manoeuvres, additional observations over the next few days will resolve the eccentricity question. The above solutions move my estimate of the date of the manoeuvre(s) to Aug 9, between 17 h and 21 h UTC. Observers may wish to use both of the above, to get an idea of the range of possible paths the object may follow. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l

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