04-12-2025, 08:14 PM
Maybe ' Sight Reduction' for S/R? The 43.20 might be shorthand for 43 degrees and 20 minutes. I have two of the Mk IX BM sextants that Flt Sgt Thompson would most probably be using. They have a switch to insert an additional 5 degrees altitude that, in theory, requires a different index error for the sight reduction. Unfortunately, this suggestion for '5 DR' doesn't tie in with the 43.20 idea - the 5 degree switch is not required for this reading. Both my sextants are in good order and I use them to take Sun, planet and star sights from the back garden. I can understand Peter Hoare's comment about the accuracy - they work well enough from a chair on solid ground but the astrodome of a Lancaster would be another matter!
Neil_s
Neil_s