hi, L.  i didn't put those last two in (with the log(cos) stuff).  it didn't come from Gilson AFAIK.  you'll have to check the article history (the "diffs") to figure out who put it in.  you can yank it out AFAIC and see if someone squawks or not (i won't), or you can track down the editor who stuck it in and ask them about it or you can yank it out and tell that editor or any other combination.  BTW, G is accurate to 150 ppm where that number above is 42 ppm (better than G but not much better).  nonetheless, we know α to about 3 ppb and Gilson's numerology is accurate to about twice that error.