[CQ-Contest] Predicting Unusual Openings

[Eric Scace K3NA]

The answer to this question is location specific.  However, there are "leading
indicators" that can warn when conditions might permit an unusual opening,
sometimes hours in advance.  And while the indicators and openings vary from
place to place, it's useful to know what other people in other locations are
relying on.  It might help you figure out something that will happen to you.

Useful indicators can be created without relying on Old Timers for advice (and,
sometimes, even surprise the Old Timer who thought he knew them all).

An example from Maryland:  The path from Kazakhstan to Maryland is similar in
shape to the path from Maryland to Japan.  If I can work stations in Kazakhstan
(the few that exist), I know that in about 8-9 hours there is a good chance for
an opening to Japan.  In years with modest solar activity, a 10m or 15m opening
to Japan might not happen.  Working a Kazakh station on 10 or 15 will encourage
me to check for Japan/east Asia on that band later.

Many paths can be similarly analyzed.  Want to find an indicator for whether
country X can be worked?  Carefully map out the path from your QTH to X.  Note
how close it comes to the auroral zone (or note geomagnetic latitude at the
extreme north or south ends of the path).  Then draw a "mirror path" of similar
length which reaches equally north/south (from a geomagnetic latitude
perspective).  Note the location "Y" at the far end of the path which is a
similar distance away, and (hopefully) similar geomagnetic latitude at the
endpoint.  Determine the degrees of longitude between your QTH and X or Y;
divide by 15 to get the number of hours "T" it takes for the earth to rotate
that angle.  Then start paying attention on the air, or checking your old
contest logs.  When did I work stations in "Y" on the band of interest?  Did I
work stations in "X" about "T" hours later on that band?  Did I ever work
stations in "X" without working stations in "Y" about "T" hours earlier?  If the
answer to the last two questions is reasonably consistent (usually work Y and
then X... rarely work X without working Y), then you've found an indicator for
the path in question.

Maybe other people do this, but I haven't heard about it.  So I tentatively will
claim this as the "K3NA Mirror Path Technique".

Unfortunately, not all such "mirror paths" are helpful.  Many mirror paths
terminate in places without any ham population.

A second approach is to study propagation paths (long and short) with
ray-tracing software.  These models will give you a hint about how close a
signal comes towards the target location when the band is normally closed on
that path.  Then check that path whenever the model indicates that the signals
"almost get there" -- on some days the ionosphere will be more favorable than
average and you can get that last hop... that needed chordal leap... or a moment
of low absorption.  (Many years ago, someone [I think a W4] gave a great talk at
Dayton on long path openings with similar analysis.  He had made scheduled
attempts with other DXers in those locations at times when long path might work,
and was gratified to see how often it did!)  This is the "Do Your Homework"
technique.

Other openings just require work and attention to detail.  Here are two examples
which have been described by others:

In the few days leading up to a contest where you intend to make a serious
effort, get on the radio and listen.  Keep records on when you start to hear
stations for key openings (or potential openings identified in the propagation
study described above) on each band... and when you stop hearing them at the end
of the opening.  By comparing days, you'll be able to determine that, for
instance, 15m has been opening 15 minutes earlier each day to Europe...
indicating that conditions are improving and that an effort to check on 10m
should be made.  Records like this that we kept at Rotuma during the 3D2XX
expedition tipped us off that the European 15m over-the-pole midnight opening
was improving from a few minutes one day only to OH (i.e., we worked a few,
asked the JAs to QRX, and then worked a bunch for 5-10 minutes)... a little
longer and deeper the next day (we knew when to ask the JAs to QRX)... and
starting even earlier the following day.  That day we asked stations to also try
10m, and were rewarded with a one-day-only opening on 10m (nighttime for us)
over the pole into Europe... strong signals for maybe 45 minutes, giving many
Europeans a rare, difficult (especially at that point in the sunspot cycle) 10m
QSO into the deep Pacific.  (And a special thanks to all the JAs that stood by
while we worked Europe until the opening faded.)

On higher bands, check the band REGULARLY beginning two hours before its normal
opening time and again for two hours after its normal closing time.  (If the
band is dead, it doesn't take long to check!)  Many times there are brief, spot
openings on skewed paths... or coupled in with E-skip.  Two dramatic ones I've
caught from Maryland in this way were a 2am opening long path to southeast Asia
on 15m with huge signals... and a 4am 20-minute opening to OK, HA, YU, and I (in
sequence) on 10m near the bottom of the sunspot cycle (probably E-skip and maybe
a duct).

It would be great to see a list of indicators, sorted by location, month, and
solar activity level, accumulated on a web site somewhere.

-- Eric K3NA





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