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    Re: A celestial navigation mystery.
    From: Gary LaPook
    Date: 2011 May 11, 01:52 -0700
    Mystery still not solved.

    A few observations. Certainly  most of the handwriting is Noonan's but the notation about the ship President Harrison is not his hand.

    I suspect that some of the labels may have been added after the flight allowing for the wrong name of the star to sneak in. A good example of this is the notation for the Alphecca line that says "ADV" showing the Alphecca line advanced to 0446 Z to cross with the Polaris line to form the 0446 Z fix. There would be no reason for the navigator to make that notation unless, after the flight, he was explaining the chart work to someone.

    I still wonder if the actual plotting wasn't done by Harry Manning and Noonan just wrote in the labels at a later time. I base this on the arrows showing the azimuths and these arrows do not appear on Noonan's Atlantic crossing chart. It seems strange that Noonan would change his method of plotting LOPs in just three months. When I plot LOPs I never draw in the azimuth line since I use the "flip-flop" method with an aeronautical plotter. It is possible that Noonan used the method that I use and that Manning used parallel rules.

    Thinking about Greg's suggestion I planned to do the calculation for Denebola using H.O. 208 and then see if some easy type of error would produce the 82° erroneous Zn. But on further thought I realized that I didn't have to do this to eliminate Denebola.

    I calculated the data for each of the observations. Then by examining the chart it is clear that the intersection of the ZN line with a parallel of latitude is the AP. My calculated GHAs corresponded with the longitudes of these intersections. This provided a way to eliminate potential candidates since the correct star would have to have a GHA with the minutes equal to the measured longitude of the intersection of the Alphecca Zn arrow with the 34° north latitude line. Because the Zn crosses the latitude line at a shallow angle, there is some uncertainty about the correct longitude/GHA value to use. I finally decided that any star that didn't have a GHA in the range of XXX° 17' to 26' could be eliminated. This took out Denebola which had a GHA of  66° 50.9', outside of the acceptable range. This also eliminated Aldebaran, GHA 175° 14.4', also outside of the range.

     Keith suggested Alpha Lyncis  but that looses out on several counts. First, it is not one of the 57 listed stars in the Nautical Almanac. Giving it some thought, I have never shot any other stars, I have never gone to the back of the Almanac to use one of those other 173 stars, have you guys? The only reason I can see for using one of them is if one the 57 stars were not available. But since you don't use these other stars on a regular basis and, presumably the familiar stars are not visible, how do you know what star you are shooting through that hole in the clouds. On a ship where your DR is much more accurate than in a plane you can take plenty of time and do some calculation to figure out the identity of the mystery star but I can't see doing this in a plane.

    A second reason to eliminate this star is that it is not even one of the 173 other stars in the almanac so Noonan couldn't have used it.

    A third reason is that its GHA also falls outside of the acceptable range (assuming that its SHA hasn't changed significantly since 1937). Its RA is 09h 21m 03.46
    making its SHA 219° 44' which produces a GHA of 103° 03.3', outside the range.

    So, the mystery continues.

    gl





    --- On Tue, 5/10/11, Keith Pickering <keith_pickering@yahoo.com> wrote:

    From: Keith Pickering <keith_pickering@yahoo.com>
    Subject: [NavList] Re: A celestial navigation mystery.
    To: NavList@fer3.com
    Date: Tuesday, May 10, 2011, 9:46 AM

    My measurement of the azimuth puts it at 81°, which suggests Alpha Lyncis as the most likely target. Not particularly bright at 3, but with a similar name and in the right place in the sky: high and east. Denebola would have been south of due East, which pretty much rules it out.

    Keith Pickering



    From: Gary LaPook <glapook@pacbell.net>
    To: NavList@fer3.com
    Sent: Mon, May 9, 2011 3:06:13 AM
    Subject: [NavList] A celestial navigation mystery.

    I have been investigating Fred Noonan's navigation of the Amelia Earhart flight. On March 18, 1937 the plane flew from Oakland to Hawaii on the first leg of what was supposed to be a westbound around the world flight. But when they were taking off for the next leg from Hawaii to Howland, Earhart lost control of the aircraft and it crashed, never having lifted off of the runway on Ford Island in the middle of Pearl Harbor. The plane was crated up and sent back aboard a ship to California for repairs. After the repairs Earhart flew the route eastbound and disappeared flying from Lae to Howland on July 2, 1937.

    The charts used for the Oakland to Hawaii leg as well as charts for the earlier legs of the eastbound flight are kept in the archives of Purdue University. I paid the archivist to scan several of these charts for me (not cheap) so that I could examine Noonan's chart work. I am attaching one of his charts showing a portion of the Oakland to Hawaii leg.

    There is a mystery on this chart and I am hoping that the knowledgeable members of this group can solve this mystery since I haven't been able to. You will see on the chart a 0446 Z fix at approximately 34° north, 132° west. This fix was made up of a 0432 Z Alphecca line advanced to cross the 0446 Z Polaris line. (The 0442 arrow is a radio bearing, not a part of the mystery.) We have no more information than this chart, not Noonan's work sheet, nor his actual sextant readings. I have been able to check his work by computing the altitudes and azimuths for the stars he used for his fixes. I don't have his altitudes to compare with my computations but I have been able to compare the plotted azimuths with my work and his azimuths agree with mine. I think this shows that he probably computed his altitudes correctly since, when using H.O. 208, the azimuths are computed after the altitudes they would probably not be correct if the altitudes were not also correct.

    For the 0446 Z fix, the azimuth of Polaris (not surprisingly) is 360°. I measured the azimuth of his 0432 Z Alphecca line and I get 082° true. We can see that he re-started his DR from this fix so he must have considered it to have been a good fix. There is one little problem, however. Alphecca would not have been visible at that time and would not rise in that location for another hour. So what star did Noonan shoot? I haven't been able to find any other stars that would have had an azimuth of about 082° at that time and place. I note tha Menkar would have amost a reciprocal azimuth but the azimuth arrow definitely points to the east.

    (There is also a question in my mind, is this actually Noonan's chart work? On that first leg Manning was the chief navigator so it may be Manning's chart work. Looking at Noonan's methodology on the Natal to Dakar chart (only Noonan was on that flight) he doesn't plot the azimuth arrows. But the hand writing on both charts looks to be the same. Another mystery. I have previously posted the Natal to Dakar chart.)
    Any ideas?

    http://www.fer3.com/arc/imgx/North-Atlantic--5.jpg

    http://fer3.com/arc/m2.aspx?i=112864

    gl
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