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Bris sext. was: Re: John Rae
From: Alexandre Eremenko
Date: 2005 Oct 30, 14:48 -0500
From: Alexandre Eremenko
Date: 2005 Oct 30, 14:48 -0500
Dear John, I am glad that there is a feedback on my postings on the Bris sextant. So I continue, simultaneously answering your questions. Here are my (genuine, Bris-made, CP-sold) Bris angles. There are 8 "Suns", not counting the real one. 3 bright, 4 dim, and one (No 8) very dim. Row data from calibration observation on Jul 28, 2005, Nx refers to the Sun number x from above, UL and LL are upper and lower limbs true altitudes. The numbers are true angles for given time and place, NOT corrected for refraction and dip. Time and place were determined by the on-board GPS. The elevation was approx 6 feet, and the waves were substantial. LL UL DIFFERENCE N1: 10d04.5' 10d37.3' 32.8 N2: 12d29.5' 13d03.0' 33.5 N3: 20d39.1' 21d07.1' 28 N4: missed 23d33.3' N5: 25d31.8' 25d58.9' 27.1 N6: 33d30.5' 34d00.2' 29.7 N7: missed 35d55.8' N8: 45d53.2' 46d22.2' 29 The true Sun diameter was 31.6, according to Almanach. Alex. P.S. I have ONE more observation July 30 (of some limbs of some Suns) to compare but I never reduced it. The problems were that a) the sunny days/times were rare (North sea), and b) I had to stand my watches at the rudder, and c) I had to peel potato for the dinner, etc:-) e) When the good weather was in my free time, I did ordinary sextant observations with my SNO-T. A.