Howdy and Welcome
The Latitude/Longitude that you was given was AM19. If you get a message and you think you might want to check it out you can convert the Lat/Long at
http://www.ubootwaffe.net/quadrant.cgi
here you input the Lat/Long and it will give you the Grid area.
I am currently working on converting the Lat/Long on all Allied Ships Naval and Merchant that were either hit or sunk by U-boats in WWII. So far with all that I have converted I have played in SH3 GWX and checked the game with the current date listed. Example on Oct 14 1939 HMS Royal Oak(Battleship) was to be anchored in Scapa Flow and on that day it was sunk by U-47. Which the position was 58º55'N, 02º59'W converted was AN1614. So I went there a day before and found it there and of course I had to sink it like a good seaman. I have found that convoys and single ships are so far correct with the game with the real records of WWII. Once I compile enough I will post it for everyone to check for themselves. Have any more questions I will do my best to help out. Good Luck on your hunt.