A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Antoine Couëtte
Date: 2023 Nov 18, 18:04 -0800
This [lonesome] thread was initially triggered by Frank's "Alnair identification" quizz-thread in which Peter Blaskett made a very important contribution under the form of a quite instructive Picture showing in particular the South Pole above the horizon (left of the Picture), which fully makes sense here since the Observer's actual position is at S13°15.0'.
Accordingly, since this previous hand-drawn sketch of mine assumed to be taylored to an Observer at an approximate 13°S Latitude incorrectly represents the South Pole well under the horizon, it does require edition / correction as it actually sketches a sky view applicable to some Northern Observer.
In the enclosed attachment, I am bringing remedy to this through the following steps :
(1) - On top of this updated attachment : simply renaming the early Al Nair & Peacock into Star A & Star B without changing the initial hand-drawn sketch.
(2) - At the bottom of this updated attachment : adding a complementary sketch better taylored to the actual Observer's Lat close to 13°S - hence with South Pole showing [slightly] above the horizon then - in which it is again possible to adequately name the relevant stars as AlNair and Peacock this time.
It should noted that the initialdoes not require any modification since it is a general formula applicable to all configurations.
(3) - Finally it is also an opportunity here to correct (into bold underlined characters this time) and re-edit a few typos in my previous post which should read :
(3.1) - Start multiplying both sides by sinAz, then divide both sides by sinP and get : dP * (sinAz * cosAz / tgP ) - dAz = dP * sinLat * sin Az
(3.2) - 2.1.4 - At UT = 05h59m00.0s