Re: Cassini flyby

Bjoern Gimle (b_gimle@algonet.se)
Wed, 30 Jun 1999 10:30:28 +0200

>---Randy John <skysat@home.com> wrote:
>
>> Since Cassini will be in a hyperbolic orbit there will be NO TLE.
Standard
>> TLE's do NOT support eccentricities greater than or equal to 1 so you
must
>> use a program like SKYSAT or Horizons.
>
Jim Varney <sat_watcher@rocketmail.com>:
...
>You can make your own Cassini TLE by taking a short piece of the hyperbolic
>trajectory and fitting an elliptical orbit to it. Download topocentric
Right
>Ascension and Declination pairs from the JPL Horizons site.  The pairs
>...

Note that you don't need TLEs with Skymap - you can use a .trj file with
Seconds/Lat/Long/Height, and the Rocket Trajectory option on the main menu.
The path will be interpolated, like for satellite tracks. The time should
be in seconds after Map Time, in my example Aug.18 00:00 UTC.
An advantage over an elliptic fit to RA/Dec is that the ranges
are correct, so shadow entry/exit are correctly predicted.
A file for the whole day, built on JPL data, is available at
http://www.algonet.se/~b_gimle/cassini.htm

10800 6.1127 159.0947 24492
10920 5.6163 159.6755 22557
11040 5.0436 160.4148 20627
11160 4.3765 161.3496 18705
11280 3.5907 162.5291 16792
11400 2.6537 164.0200 14893
11520 1.5211 165.9143 13012
11640 0.1312 168.3420 11157
11760 -1.6007 171.4906 9339
11880 -3.7906 175.6356 7574
12000 -6.5859 -178.8148 5891
12120 -10.1375 -171.2689 4332
12240 -14.4778 -160.9505 2968
12360 -19.2180 -147.1605 1905
12480 -23.2410 -130.1506 1279
12600 -25.2474 -112.1001 1208
12720 -25.0702 -96.0484 1705
12840 -23.6251 -83.5178 2674
12960 -21.7981 -74.2975 3975
13080 -20.0335 -67.5862 5494
13200 -18.4779 -62.6494 7151
13320 -17.1500 -58.9563 8899
13440 -16.0262 -56.1472 10706
13560 -15.0736 -53.9802 12553
13680 -14.2613 -52.2905 14428
13800 -13.5635 -50.9634 16324
13920 -12.9592 -49.9173 18233
14040 -12.4318 -49.0929 20154
14160 -11.9681 -48.4463 22081
14280 -11.5577 -47.9442 24015
14400 -11.1921 -47.5611 25953
...

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