Flare fans,
Here's a comparison of Iridium flares by latitude and month. Each table
is for the 12 months of 1998. The longitude for each table is zero
degrees, the Prime Meridian. Latitudes extend from the North Pole to
the South Pole in 15 degree steps. The orbital elements used are for
epochs 98049 and 98050 and include Iridiums through Iridium 49.
At a glance, I can only say that if you want to see Iridium flares, head
for the poles during local winter. Twenty flares a day or better! The
South Pole will be especially active this August with 1417 flares, an
average of 45 each night! Of course, those nights are 24 hours long.
Don't expect to see much under the midnight sun at either pole, though.
By all means, avoid the equatorial zones. Note that "lucky" observers
at Lat 0, Long 0 will see one (1) flare in April, assuming perfect
weather.
There are clear seasonal effects at mid and high latitudes, but some
features are puzzling. Look at latitude -45, for instance, with the
abrupt drop to only six flares in August. You can see the midnight sun
effect starting at latitude +60 in June, which has zero flares. It's
very obvious for + and - 90 degrees, which are virtually mirror images
of each other.
If anybody wants the raw output files these charts are distilled from,
email me. They're in one line non-verbose format. Zipped, they total
about a quarter megabyte. If you have any kind of reasonably speedy
computer, you can compute a years worth of flares for your own
location. The Pentium 90s I used take about fifteen minutes to do a
years worth of mid-latitude calculations. Be aware that execution times
increase sharply for the poles. Even with a slow computer, you can
start the calculation and let it run overnight or while you're at work.
Dave Mullenix
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Latitude 0
Month Total Flares AM Flares PM Flares Max Mag
1 3 3 0 -5
2 7 3 4 -7
3 4 3 1 -8
4 1 0 1 -2
5 7 5 2 -6
6 6 4 2 -6
7 2 2 0 -5
8 3 1 2 -8
9 5 2 3 -8
10 6 6 0 -7
11 6 5 1 -7
12 4 3 1 -6
Latitude +15
Month Total Flares AM Flares PM Flares Max Mag
1 9 7 2 -7
2 6 3 3 -7
3 6 5 1 -8
4 5 1 4 -8
5 4 2 2 -6
6 6 2 4 -8
7 2 1 1 -3
8 2 0 2 -6
9 7 2 5 -8
10 5 3 2 -8
11 3 2 1 -8
12 6 3 3 -6
Latitude -15
Month Total Flares AM Flares PM Flares Max Mag
1 4 3 1 -5
2 8 5 3 -6
3 3 3 0 -8
4 3 1 2 -8
5 7 5 2 -7
6 7 5 2 -9
7 10 6 4 -8
8 4 0 4 -7
9 3 1 2 -4
10 4 1 3 -8
11 1 0 1 -3
12 4 2 2 -7
Latitude 30
Month Total Flares AM Flares PM Flares Max Mag
1 8 6 2 -8
2 7 6 1 -7
3 4 3 1 -3
4 6 1 5 -8
5 8 4 4 -6
6 22 14 8 -9
7 13 13 0 -6
8 7 2 5 -5
9 3 1 2 -3
10 5 2 3 -7
11 6 3 3 -8
12 4 2 2 -3
Latitude -30
Month Total Flares AM Flares PM Flares Max Mag
1 15 10 5 -6
2 9 3 6 -7
3 5 4 1 -7
4 8 3 5 -8
5 11 5 6 -9
6 12 9 3 -8
7 21 18 3 -7
8 4 0 4 -7
9 4 3 1 -7
10 5 2 3 -8
11 7 3 4 -8
12 19 18 1 -7
Latitude 45
Month Total Flares AM Flares PM Flares Max Mag
1 22 16 6 -8
2 17 10 7 -8
3 10 5 5 -8
4 17 6 11 -8
5 33 23 10 -8
6 18 12 6 -8
7 20 6 14 -8
8 29 21 8 -8
9 6 3 3 -4
10 9 4 5 -5
11 14 8 6 -8
12 6 3 3 -7
Latitude -45
Month Total Flares AM Flares PM Flares Max Mag
1 25 15 10 -7
2 11 6 5 -8
3 7 7 0 -7
4 9 5 4 -7
5 12 8 4 -8
6 13 11 2 -7
7 20 12 8 -8
8 6 1 5 -8
9 13 6 7 -8
10 22 11 11 -8
11 28 21 7 -8
12 41 22 19 -8
Latitude 60
Month Total Flares AM Flares PM Flares Max Mag
1 26 20 6 -8
2 27 18 9 -8
3 33 20 13 -8
4 30 18 12 -8
5 11 8 3 -5
6 0 0 0 0
7 16 2 14 -8
8 45 24 21 -8
9 24 9 15 -8
10 20 11 9 -8
11 35 18 17 -8
12 11 5 6 -9
Latitude -60
Month Total Flares AM Flares PM Flares Max Mag
1 6 6 0 -8
2 23 21 2 -8
3 23 10 13 -8
4 13 9 4 -8
5 23 17 6 -8
6 28 20 8 -8
7 18 8 10 -9
8 10 1 9 -8
9 31 14 17 -8
10 36 26 10 -8
11 17 9 8 -8
12 4 4 0 -8
Latitude 75
Month Total Flares AM Flares PM Flares Max Mag
1 83 52 31 -9
2 134 91 43 -8
3 83 46 37 -8
4 2 2 0 -5
5 0 0 0 0
6 0 0 0 0
7 0 0 0 0
8 0 0 0 0
9 83 76 7 -8
10 143 126 17 -9
11 111 34 77 -8
12 146 51 95 -8
Latitude -75
Month Total Flares AM Flares PM Flares Max Mag
1 0 0 0 0
2 0 0 0 0
3 124 108 16 -9
4 136 82 54 -8
5 89 57 32 -8
6 112 46 66 -8
7 120 34 86 -9
8 95 32 63 -9
9 95 44 51 -8
10 10 7 3 -7
11 0 0 0 0
12 0 0 0 0
Latitude 90
Month Total Flares AM Flares PM Flares Max Mag
1 566 309 257 -8
2 592 308 284 -9
3 443 245 198 -8
4 0 0 0 0
5 0 0 0 0
6 0 0 0 0
7 0 0 0 0
8 0 0 0 0
9 0 0 0 0
10 242 139 103 -9
11 592 297 295 -8
12 436 233 203 -8
Latitude -90
Month Total Flares AM Flares PM Flares Max Mag
1 0 0 0 0
2 0 0 0 0
3 0 0 0 0
4 109 54 55 -8
5 841 501 340 -8
6 271 156 115 -8
7 374 196 178 -8
8 1417 768 649 -9
9 0 0 0 0
10 0 0 0 0
11 0 0 0 0
12 0 0 0 0