The following elements have been derived from observations by Leo Barhorst, Russell Eberst, David Hopkins, Marco Langbroek and Mike Waterman: USA 276 388 X 411 km 1 42689U 17022A 17152.86247769 .00006220 00000-0 86095-4 0 01 2 42689 50.0059 119.2214 0016511 115.4222 244.8457 15.56232863 06 Arc 20170528.83-0601.88 WRMS resid 0.067 totl 0.006 xtrk Below are updated conjunction estimates for the closest approaches on 2017 Jun 03 with range <= ~100 km. ISS sub-satellite point USA 276 sub-sat point ------------------------- ------------------------- TCA Range Lat Lon Alt Lat Lon Alt UTC km deg deg km deg deg km 11:43:10 83.67 43.32 N 170.77 E 410.56 43.71 N 169.99 E 391.44 12:29:09 54.02 43.96 S 22.37 W 418.35 44.16 S 22.93 W 424.13 13:15:32 25.13 43.80 N 146.22 E 410.72 43.88 N 146.06 E 391.49 14:01:47 13.03 43.90 S 45.77 W 418.32 43.86 S 45.65 W 424.01 14:47:54 52.76 44.27 N 121.64 E 410.88 44.04 N 122.12 E 391.54 15:34:24 77.36 43.87 S 69.25 W 418.30 43.57 S 68.45 W 423.90 16:20:16 115.99 44.73 N 97.05 E 411.04 44.20 N 98.19 E 391.60 The time and range of closest approach is fairly sensitive to the argument of perigee, eccentricity and decay rate of USA 276, which may not yet have settled down to their actual values, due to the still short observational arc. For USA 276, I used the above TLE. For ISS, I used NASA's current estimated TLE for June 3: https://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html 1 25544U 98067A 17154.59563174 .00016717 00000-0 10270-3 0 9050 2 25544 51.6397 106.0758 0004758 233.6745 126.3969 15.53986584 19633 If the intention is to perform an actual rendezvous, instead of, or in addition to a series of fly-bys, then USA 276 could manoeuvre to match the plane of ISS near one of the above times. If delta-V is a significant constraint, then the minimum energy manoeuvre would occur on Jun 24, when USA 276 and ISS would have the same RAAN, leaving only a 1.6 deg change of inclination. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Fri Jun 02 2017 - 07:10:44 UTC
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