I have used Paul Gabriel's observations: http://www2.satellite.eu.org/seesat/Aug-2000/0256.html to produce the first Lacrosse 4 parking-orbit elements from observations, and to revise my post-manoeuvre search elements. Since there are still too few points to produce a complete orbital analysis, I made use of the Titan 2nd stage orbit, for which the official elements were: Lacrosse 4 r 9.8 3.0 0.0 4.8 v 1 26474U 00047B 00232.45120305 .00006795 00000-0 83219-3 0 96 2 26474 68.0033 35.0324 0073427 179.4307 180.6939 14.81793814 222 To produce the Lacrosse elements, I manually adjusted the epoch and mean motion to reflect the fact that it trailed its 2nd stage by about 63 s, and I added a reasonable rate of decay. Finally, I used Elcor to adjust only the RAAN and mean anomaly to fit Paul's points, with this result: Lacrosse 4 18.0 4.5 0.0 3.6 v 1 26473U 00047A 00232.45193222 .00002000 00000-0 24527-3 0 06 2 26473 68.0033 35.0594 0073427 179.4307 180.6777 14.81066426 08 I used the parking orbit to revise my predicted post-manoeuvre elements, with this result: Lacrosse 4 18.0 4.5 0.0 3.6 v 1 70007U 00232.99197917 .00001500 00000-0 27197-3 0 01 2 70007 68.0033 33.5777 0005500 178.8486 180.1000 14.66165000 09 This corresponds to a manoeuvre on 2000 Aug 19 at 23:48:47 UTC, at the apogee of the parking orbit, over 1.1 S and 67.4 E, headed northbound. Of course, there is no guarantee that the manoeuvre will take place when predicted, so observers should run predictions for both the parking orbit and the post-manoeuvre search orbit. Ted Molczan ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Sat Aug 19 2000 - 12:24:43 PDT