Re: TLE format after Dec 31

Bjoern Gimle (b_gimle@algonet.se)
Mon, 27 Dec 1999 08:27:55 +0100

>My program is ELE_MAN9.EXE but is not ready for release. :-(  I'm sure
>there are other programs though which also fully address the issue.
>
I tried the programs I use most: VEC2TLE, SKYMAP and IRIDFLAR.
VEC2TLE can re-epoch elsets (using the 'Impulsive Delta-V' function)
correctly across the coming New Year, and SkyMap and IridFlar can predict
into the new millenium, and use the elsets generated for year 00, with
consistent results with starting dates either before or after New Year.

Iridium 8        4.0  1.8  0.0  6.0 d 11.5       779 x 776 km
1 24792U 97020A   99353.34739880 -.00000147  00000-0 -59428-4 0  3049
2 24792  86.3979 108.8121 0001951  45.6870 314.4473 14.34216978137333
processed with VEC2TLE and edited gave:
Iridium 00
1 24792U              2.16159145 -.00000147  00000-0 -59428-4 0  3053
2 24792  86.3979 103.0402 0001951   0.7105 359.4093 14.34212386139322

IridFlar produces:
Ir# S   Date   Local Time Azm El   RA   Decl  (km)  N Ill Azm  Elev ...
--------------------------------------------------------------------
 8     0- 1-11 10:27:50.5 064 79 19h32  62.4  802.6 D Lit 160   7.1 ...
00     0- 1-11 10:27:50.5 064 79 19h32  62.4  802.6 D Lit 160   7.1 ...

00     0- 1-15  9:54:23.0 069 67 20h49  59.7  848.1 D Lit 152   5.9 ...
 8     0- 1-15  9:54:23.0 069 67 20h49  59.8  848.2 D Lit 152   5.9 ...
--------------------------------------------------------------------

SkyMap gives (external sort places 0/ before 99/):

 0/ 1/ 3 11:34:11 319 67  11:34:45 269 75  11:35:20 217 67   5.5 24792
Iridium 00
...
 0/ 1/11 10:27:18  20 67  10:27:57  82 79  10:28:37 147 67  -2.2 24792
Iridium 00
 0/ 1/11 10:27:18  20 67  10:27:57  82 79  10:28:37 147 67  -2.2 24792
Iridium ...
 0/ 1/15  9:54:22  68 67   9:54:32  80 68   9:54:42  94 67   1.9 24792
Iridium 00
 0/ 1/15  9:54:22  68 67   9:54:32  80 68   9:54:42  94 67   1.9 24792
Iridium ...
99/12/31 11:33:55   5 67  11:34:38  81 85  11:35:21 163 67   4.7 24792
Iridium


SkyMap and IridFlar also treat 2000 as a leap year, evidenced by:
 0/ 2/28 18:34:47 112 67  18:35:03  91 69  18:35:20  69 67   5.1 24792
Iridium 8
 0/ 3/ 2 18:34:30 178 67  18:35:13  96 88  18:35:57  11 67   5.3 24792
Iridium 8
 0/ 3/ 5 18:34:55 234 67  18:35:26 278 73  18:35:57 322 67   5.7 24792
Iridium 8
since Iridiums make close to 43 orbits in three days.
IridFlar does report a flare on the middle pass above (for me).

SkyMap also shows consistent RA change of the Sun and Moon across
both month-ends.

I have only tested the most used functions of the programs, and so far
no elset with large perturbations.







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