Cassini flyby
Randy John (skysat@home.com)
Tue, 22 Jun 1999 01:16:15 -0700
I can't help Ed with Giotto, but I can with Cassini.
Cassini will make an earth flyby at 1999-Aug-18 03:28 UT nearly
over Easter island at an altitude of 1173 kilometers.
Observers in South America will have a near view of the space-
craft. Those in North America will have a not so near view.
Europe will be in morning twilight. Other areas will be in
daylight.
The TELNET version of Horizons gives this state vector (the WWW
version doesn't know about state vectors):
pfile_redesign_v2m189d.n
2451408.500000000 = A.D. 1999-Aug-18 00:00:00.0000 (TDB)
-.1846909838200464E+06 0.7967070634416329E+05 0.4263070908016452E+05
0.1417157944366931E+02 -.6815065498345841E+01 -.3603906365487077E+01
Horizons can be found at http://ssd.jpl.nasa.gov/horizons.html.
Here is the same vector in SKYSAT format:
CASSINI
1 XYZ KM 99230.00000000 -184690.98 79670.706 42630.709
2 14.17157943 -6.815065498 -3.603906365X
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.
Here is the Horizons output for my location.
Date__(UT)__HR:MN R.A.__(r-apparent)__DEC Azi_(r-appr)_Elev delta
deldot
1999-Aug-18 04:30 Ar 23 17 46.54 -11 53 50.9 106.7806 1.9938
0.0004149237 15.91196
1999-Aug-18 04:40 m 23 19 31.97 -11 02 13.1 107.4146 4.1022
0.0004786968 15.89621
1999-Aug-18 04:50 m 23 20 44.84 -10 21 33.7 108.2975 6.1934
0.0005424102 15.88230
1999-Aug-18 05:00 m 23 21 38.73 -09 49 01.6 109.3600 8.2506
0.0006060727 15.87077
1999-Aug-18 05:10 m 23 22 20.14 -09 22 29.1 110.5609 10.2726
0.0006696939 15.86163
1999-Aug-18 05:20 m 23 22 52.74 -09 00 26.8 111.8747 12.2609
0.0007332833 15.85474
1999-Aug-18 05:30 m 23 23 18.85 -08 41 51.8 113.2856 14.2165
0.0007968495 15.84988
1999-Aug-18 05:40 m 23 23 40.01 -08 25 58.9 114.7838 16.1399
0.0008604002 15.84688
1999-Aug-18 05:50 m 23 23 57.32 -08 12 15.2 116.3636 18.0310
0.0009239425 15.84553
1999-Aug-18 06:00 m 23 24 11.56 -08 00 15.8 118.0219 19.8889
0.0009874828 15.84569
1999-Aug-18 06:10 m 23 24 23.33 -07 49 42.1 119.7577 21.7122
0.0010510268 15.84723
1999-Aug-18 06:20 m 23 24 33.08 -07 40 19.3 121.5713 23.4992
0.0011145799 15.85001
1999-Aug-18 06:30 m 23 24 41.17 -07 31 56.2 123.4641 25.2475
0.0011781468 15.85393
1999-Aug-18 06:40 m 23 24 47.87 -07 24 23.4 125.4384 26.9546
0.0012417319 15.85891
1999-Aug-18 06:50 23 24 53.41 -07 17 33.8 127.4969 28.6174
0.0013053394 15.86486
1999-Aug-18 07:00 23 24 57.98 -07 11 21.2 129.6428 30.2325
0.0013689729 15.87170
"Delta" is in AU's so at 6:00 the elevation is 20 degrees and the range
is nearly 148,000 km. Almost as bad as Giotto.
In Austin, Ed will have a nice view with a range of 50,000 km, elevation 20
degrees at 4:20.
An observer at -75.0000, -15.0000 (near Lima, Peru) will have a much more
reasonable range of 3485 km at 3:33 and an elevation of 42 degrees.
Randy
p.s. A nice web page by Troy Goodson (a member of the Cassini
Flight Path Control Group) is at : http://www.csun.edu/~kg46825/cassini/.
p.p.s. Horizons doesn't know about Giotto.