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Re: Star-to-star distance for sextant calibration?
From: Paul Hirose
Date: 2019 May 21, 22:47 -0700
From: Paul Hirose
Date: 2019 May 21, 22:47 -0700
On 2019-05-21 15:32, Tony Oz wrote: > It's a pity I still cannot get the columns' (φ+D) and (φ-D) meaning... A couple of us have tried to explain that those columns are probably the refraction correction at upper and lower culmination of the star. In my previous post the numbers I calculated for Kochab are very close to the values in the document. Here are refraction corrections for the Polaris to Vega distance at latitude 60, with values from the document in parentheses. Vega (D = 51.6) lat = 60 h = 10, refr. = 4.59' (4.7) h = 20, refr. = 2.02' (2.0) h = 30, refr. = 1.31' (1.3) h = 40, refr. = 1.04' (1.1) h = 50, refr. = 0.95' (1.0) h = 60, refr. = 0.93' (1.0) upper culmination 0.94' (1.0) lower culmination 5.36' (5.6) Altitude at lower culmination is only 8.8°, so the discrepancy in refraction (T = 10 C and P = 1010 mb) is not surprising.
