Hi all, If something doesn't go wrong again, NROL-71 will finally be launched from Vandenberg SLC-6 on December 19 (December 18 local time for the US) near 1:57 UT. Ted recently already discussed the peculiarities of this launch. It might be an electro-optical payload, but in an unusual, ~74 degree inclined and (surprise) non-sunsynchronous orbit. Here are a couple of potential search orbits for NROL-71 assuming launch on 19 December 2018, 1:57 UT: For KH-11-like orbital altitudes but 74-degree inclined non-sunsynchronous: NROL-71 265 x 1000 km KH-11-like 1 70001U 18999A 18353.08125000 .00000000 00000-0 00000-0 0 03 2 70001 074.0000 189.3102 0524203 155.2439 326.4145 14.78994708 02 NROL-71 265 x 500 km KH-11-like 1 70002U 18999A 18353.08125000 .00000000 00000-0 00000-0 0 04 2 70002 074.0000 189.3102 0173800 155.2439 324.5345 15.61785606 05 NROL-71 265 x 455 km KH-11-like 1 70003U 18999A 18353.08125000 .00000000 00000-0 00000-0 0 05 2 70003 074.0000 189.3102 0140989 155.2439 324.3567 15.69614809 06 #70003 best fits the RAAN precession that Ted in his analysis deduced from the change in launch time with date. A last option is this one, for a Lacrosse-like orbital altitude but 74-degree orbital inclination: NROL-71 715 x 725 km Lacrosse-like 1 70004U 18999A 18353.08125000 .00000000 00000-0 00000-0 0 06 2 70004 074.0000 189.3662 0007044 155.2265 327.0336 14.51731413 04 I noted that the inclination of the first generation FIA radars, launched into 123 degree inclined orbits, was basically the retrograde complementary of the prograde 57-degree inclination of Lacrosse 5. The first of the new generation FIA radars (FIA R5) was recently launched into a 106 degree inclination: and coincidence or not, this is the retrograde complementary of the prograde 74-degree inclination now indicated for NROL-71. Hence, I wonder whether the payload could perhaps be a Lacrosse-like Radar, although there is many to be said against that option. Ted's option for a 265 x 455 km KH-like orbit (i.e. #70003) fits the Hazard Areas very well, so is likely the best option. The orbits above give evening twilight visibility from NW Europe on the first day (December 19) plus some very low morning passes. - Marco ----- Dr Marco Langbroek - SatTrackCam Leiden, the Netherlands. e-mail: sattrackcam_at_langbroek.org Cospar 4353 (Leiden): 52.15412 N, 4.49081 E (WGS84), +0 m ASL Cospar 4355 (Cronesteyn): 52.13878 N, 4.49937 E (WGS84), -2 m ASL Station (b)log: http://sattrackcam.blogspot.com Twitter: _at_Marco_Langbroek ----- _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Fri Dec 14 2018 - 11:12:16 UTC
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