Pass Predictions

Many satellite operators use many different methods to predict when a satellite will pass over them.  These “pass predictions,” as they are often referred to, are important when choosing a time to operate satellites.

I’ve often thought about an easy way to track/predict without the need for computing device.  Sometimes this is handy in wilderness situations.

Interestingly enough, Bob WB4APR posted his thoughts about this on the AMSAT-BB:

Actually, using simple pass-times, it is possible to predict with a simple
pencil, all future pass times for several weeks.

Every satelite REPEATs their daily ground track every few days or so.
AO51 repeated every 5 days, and GO32 every 9.  These were sun synchronous
and so not only the ground track repeated but the time of the passes
repeated as well.

See the examples on:

The ISS is not sun synchronous, but these three rules will predict future
ISS passes without any stinkin-confusor:

1) If you hear one  pass, 5 out of 7 times, the next one is about 90
minutes later.

2) The ISS REPEATS the same ground track every other day but 51 minutes

3) For a given day, the same pass the next day is 23 minutes later.

This makes portable APRS operations in the wilderness easy.  All you need
is ONE PASS time, and you can infer all the others for weeks using the
simple rules, and just keepin notes on pass TIMES when heard.
You don’t need no-stinkin-computer.  Satellites are in “orbit” and
completely predictable.
Just take your favorite satellite, print out a week of passes, and then
look for the “RULE” that will predict future passes.  Then all you need to
remember, is the RULE.
Bob, WB4aPR

Normally I use a combination of software to predict passes.  SatPC32 and Nova for Windows on my computers.  HamSatDroid and PocketSat 3 on my Android Phone

If you don’t own any prediction tools, I recommend buying SatPC32 from AMSAT.  The proceeds go to building and launching new satellites.  The author is very reachable and supports it very well.

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