Mmm.. here's some more information:

The musical key of the melody is the first letter (only one valid possibility) of
one of the directional headings North, East, South, West. (E??)

There are 9th notes in the secret melody. Treat these as a major second off
the root note one octave up.

They are the highest notes in the scale and should be easy to discern.

The scale used in the secret melody is the major scale (in the key discussed above) also known as Ionian mode.

Does any of that change anything, notes-wise?

Lastly, these Notes must eventually map into a set of coordinates, some of the digits of which are KNOWN (or "given"):

The first seven notes: 45 29.???
The second seven: 75 3?.???

So, letmesee: if the first note(4) is "A", then the first note of the second seven has to be three notes higher (7) , which is "D". Good.

And the second note of each half (5 for both) should be one higher than "A", which it is ("B"). So far, so good.

But the F# F#(octave) confuses me slightly, as it should map to "29", I think.
Assuming that's okay anyway, I get 45 29.378 and 75 36.243 as the coordinates. But the "36" looks unlikely -- I was expecting a smaller value than "6" in that digit.

Do the extra clues make a difference to your ear now?

Thanks Tony!