Iridium flare pattern repeatability

=?ISO-8859-1?Q?Bj=F6rn_Gimle?= (b_gimle@algonet.se)
Tue, 23 Feb 1999 19:00:27 +0330 (GMT+03:30)

I have remarked long ago that there is no inherent timing
of the operational Iridiums that could cause repetitions.
The return of a single satellite at the same time three days
later is of no use since the orbital plane has precessed,
and all other patterns are quicly erased by the changing
declination and meridian transit of the Sun.

I have however at times noted some sequences for limited
periods, depending on season and orbital plane positions:

The same satellite can flare brightly every third day.

Different satellites can flare brightly a few minutes
earlier (usually) or later each day (or every other day).

The latter case is obvious in a prediction I made for a
friend going to Melbourne, Australia. The tracks are moving
slowly E to W, coming to a halt a few km W of Melbourne,
then picking up eastward speed again.

(I am not certain if the Time Zone is correct).
Edited IridFlar output:

Latitude: -37.81700  Longitude:  144.96700  Altitude:    44.0 m 
Time Zone: UTC +11.0 h

                       Iridium     Solar     Flare      Maximum Flare Bearing
IrS   Date   Local Time Azm El N Azm  Elev M Angle  Mag Lat.   Long.   (km)
-----------------------------------------------------------------------------
14T 99- 2-16 22:03:50.9 187 11 D 235 -19.1 R  0.15 -5.6 -37.77  145.10 12.7 E
13  99- 2-16 22:04:40.9 187 11 D 235 -19.3 R  0.11 -5.6 -37.78  145.06  9.7 E
50  99- 2-17 21:58:24.5 187 12 D 237 -18.5 R  1.08  0.3 -38.05  144.17 74.0 W
52  99- 2-18 21:42:05.5 184 19 D 240 -16.0 R  1.89  1.5 -37.59  145.83 80.1 E
10  99- 2-19 21:35:48.0 185 21 D 241 -15.2 R  1.37  0.3 -37.68  145.52 51.1 E
14T 99- 2-20 21:28:15.0 184 24 D 243 -14.2 R  1.49  0.5 -37.70  145.50 49.2 E
13  99- 2-20 21:29:31.4 185 23 D 243 -14.4 R  0.93 -1.0 -37.74  145.31 31.3 E
50  99- 2-21 21:23:14.8 185 25 D 244 -13.5 R  0.48 -3.2 -37.78  145.13 14.9 E
53  99- 2-22 21:16:59.0 185 27 D 245 -12.7 R  0.22 -6.5 -37.80  145.03  6.3 E
54  99- 2-23 21:10:44.9 185 29 D 247 -11.8 R  0.09 -6.9 -37.81  144.99  2.4 E
83  99- 2-24 21:04:30.9 185 31 D 248 -11.0 R  0.11 -7.0 -37.81  144.99  2.7 E
56  99- 2-25 20:58:17.8 186 33 D 249 -10.1 R  0.04 -7.1 -37.81  144.95  0.9 W
 9  99- 2-26 20:52:04.0 186 35 D 251  -9.2 R  0.09 -7.2 -37.81  144.99  2.1 E
12  99- 2-27 20:45:54.5 185 37 D 252  -8.3 R  0.38 -4.7 -37.80  145.05  8.2 E
16  99- 2-28 20:39:43.5 185 39 D 253  -7.4 R  0.58 -3.4 -37.80  145.10 12.2 E
52  99- 3- 1 20:33:31.0 185 40 D 254  -6.5 R  0.91 -2.0 -37.79  145.17 18.5 E
-----------------------------------------------------------------------------




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