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Thread: How to convert CC Grid positions to normal latitude longitude positions?

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    Default How to convert CC Grid positions to normal latitude longitude positions?

    I wonder where I can find info how to convert grid map positions used by Coastal Command in 1943 over North/Norwegian Sea like HBJT 4848 into normal Latitude and Longitude digits like 56 49 Min N 2 21 Min E?

    Just now Im specially interested to convert grid position HBJT 4848 to normal Latitude and Longitude position.

    TIA
    Juha

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    Hi,

    The codes were the same as Admiralty codes.

    A non repeating two letter code denoted the degree of Lat and Long eg HB Lat, JT Long

    The four numbers are the min lat and long eg 48' lat, 48' long.

    That was the easy bit...

    The letter code changed frequently to suit operational needs.

    Taking 1943 the validity was:
    Jan-March
    April
    May
    Jun
    July
    1-15 Aug
    16-31 Aug
    1-15 Sept
    16-30 Sept
    Nov
    1-15 Dec
    16-31 Dec

    So 12 code changes and HBJT meaning different Lat/Long for each period.

    To decypher the code you need to supply the exact date as well as the code.

    Regards
    Ross
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    Thanks Ross
    the date was 1 March 1943.

    Juha

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    56 48n 02 48e
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    Thanks a lot, Ross!
    I made my question because according to the ORB of RAF Station Leuchars on 1.Mar. 43 Beaufighter O / 235 Sqn (pilot Sgt. Vandewater, t/o 0730 Landed 1225) saw the Norwegian 600 tons trawler it was searching lying low in the water with life boats full of people round it and enemy a/c shadowing in position HBJT 4848. O / 235 attacked and claimed one Ju 88 destr and made an unsuccessful attack on a second enemy a/c.

    As you can see from http://forum.12oclockhigh.net/showthread.php?t=16603, Leo Etgen informed me that on that day LW lost Ju 88 D-5 (W.Nr. 430 206) of 1.(F)120 flown by Oberfeldwebel Hans Schubert due to unknown causes at Pl. Qu. 2719/05 Ost with all the crew listed as missing. The German position translates to 56 49 min N 2 21 min E.

    Thinking the accuracy of oversea navigation of the day IMHO it is very possible that the Ju 88 was victim of Sgt Vandewater. Of course it is impossible to be sure based only the meagre info I have.

    Thanks again for your very valuable help!
    Juha

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    Just to elaborate on the information in this thread with my own understanding, which might assist those who are converting positions with longitude West (so does not apply for Juha's example):
    The two sets of letters are for the whole degree datum immediately to the south and west of the desired position. The two sets of numbers are for the minutes north and east of that reference point (i.e find your datum point and go 'up and right' by the required number of minutes.)
    So, if CT is 23 degrees west, CT 42 is actually 22 degrees 18 minutes west (NOT 23 degrees 42 minutes west, as you might initially expect)
    Sounds confusing but makes sense once you get the hang of it. Caught me out until I realised, then the positions I was comparing matched what I expected!

    Apparently, a list of code letters may be available in National Archives ADM 186. And don't ask me what happens in the Southern hemisphere...!

    Information provided to me courtesy of the Senior Keeper, RAF Museum Department of research and Information Services (2003)
    Last edited by gbh1f; 25th March 2013 at 12:47.

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    Hello everybody,

    I am particularly interested on this conversion table for the Denmark Strait and North Atlantic for May 1941 during the hunting for the Bismarck.

    I think I have a good set of it already, I just need to complete it and find as much as possible about it.

    Can anybody help me or address me to the source ? Thanks Antonio

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