These may be what h.a.c. van asten is quoting: 2 pdf files authored by h.a.c. van asten published in the European Journal of Navigation. It may help if this thread is still valid 
Nice work, Chris--most helpful. Thanks!
Comments on the first article."While Noonan most probably used his Pioneer marine sextant to fix his position on the roads of Howland when flying at 1,000 feet altitude, with the sun in mean time whereas the true sun should be taken, it was, as we will presently see, this combination, although not being the flight's
laesio enormis, that triggered the primary impulse to not sighting the island before the fuel ran out. Both theory and practice became antagonistic to safety because the bubble sextant has its reference line which is the artificial horizon, over sun's centre and the marine sextant at sunrise registers on the optical sun's upper limb in the horizon, since due to severe refractive distortion the lower limb falls into disuse"
("Where to Search for the Earhart Lockheed Electra").Some questions:
- Did Noonan have a "Pioneer marine sextant" on the flight? How do we know that he did? In other words, what contemporaneous sources are there that back up this assertion?
- What evidence is there that the sun sight was taken at 1000'?
- What evidence is there that Noonan used "mean time" rather than "true time"?
- What evidence is there that Noonan's marine sextant was not equipped with a bubble to provide an artificial horizon? If he did have a marine sextant modified to be used in flight, how might that affect this argument?
- How do we know that Noonan used only one observation with one instrument? Doesn't the concept of a "preventer" (a second instrument carried to check errors in the use of the primary instrument) suggest using both instruments to check the validity of an observation?
This is a keeper: "When opening a can of worms there is one way only to get them in again: take a greater can (this being Zimurgi's First Law of Evolving System Dynamics)."
And this: "navigators do in the long run not get lost: they go astray for a restricted period of time."
The conclusion of the article is in the final figure: they splashed and sank in a region roughly 85 miles north-northwest of Howland.
Comments on the second article."Whatever algorithm is followed, be it H.O.208, any logarithmic gonio table, or e.g. the Douwes-Borda formula, the here recomputed endogenous outcomes remain constant: the Earhart to Herald Tribune Offices, New York, June 30, 1937 cable, reading in part: “..In addition FN has been unable [electric breakdown at Malabar radio station. auth.] account radio difficulties to set his chronometers lack knowledge their fastness or slowness..” later outdated since the 071930 GMT, 0720 by radio communicated time-coordinates group is inviolably interconnected by mathematical precomputation with heliographic time as exogenous parameter which made a structural time error impossible: the on board chronometers [and Longines hack watch] must have been perfectly synchronous with a record of the Greenwich time and for that matter: a navigator would never reset two [of three] chronometers on his own initiative, knowing thereby activating Spode´s Law [3] in its deadly configuration"
("Frederick Noonan Precomputed a Running Sunset Fix for Amelia Earhart’s Flight from New Guinea to Howland, July 2, 1937").That is one long sentence. It has many component parts. But it hinges on the claim that Noon did not get an accurate time check before leaving Lae. The evidence is from a telegram on June 30, 1937. Although this was one of the contributing factors in their failure to depart on June 30, that particular problem was rectified by
two independent time checks on July 1 and July 2. All of the computations that flow from misunderstanding of the historical record may be perfectly correct, but they are irrelevant because they are based on a faulty assumption.
