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    Re: Alnair identification
    From: Antoine Couëtte
    Date: 2023 Nov 6, 06:30 -0800

    As a complement to my last post , I decided to use 2 additional parameters - POSITION ANGLE and HEIGHT RATIO - easily measured from Frank's initial picture.

    1 - On this picture, i.e. on my printed copy at least :

    (1.1) - The position angle (PA) from Peacock to Al N'Aïr is equal to 20.0° +/- 0.5° (using my great size faithful 1970 Règle Cras) . And :

    (1.2) - The Al N'Aïr to Peacock height ratio (HR) is 130.5 mm / 64.0 mm = 2.039 +/- 0.03.

    2 - From S13°00.0' - W163°00.0' on Jan 01st, 2019 (Height of Eye = 15' , P=1013.25 mb and T = 25°C)

    (2.1) - At UT = 05h39m00.0s

    Al N'Aïr Height/Azimuth=36°24.6'/220.539° and Peacock Height/Azimuth=18°51.2'/214.185°, yielding Distance=1105.5' , PA=16.3681° and HR=1.93135

    (2.2) - At UT = 06h09m00.0s3 ( i.e. 30 minutes later)

    Al N'Aïr Height/Azimuth=31°33.0'/222.535° and Peacock Height/Azimuth=14°44.3'/214.308°, yielding Distance=1105.1' , PA=22.7040° and HR=2.14109

    (3) - Through backwards linear interpolation on both PA and HR, we get :

    For PA : UT = 05h39m + 0.5732 h    :  UT(PA) = 05h56m +/- 4 min

    For HR : UT = 05h39m + 0.5155 h   : UT (HR) = 05h54m +/- 5 min

    (4) - Overall conlusion :

    (4.1) - These 3 different UT determinations including the previous one at 05h54m are all forming a consistent set of results.

    This is a confirmation that the picture is conformal (with respect to angles).

    (4.2) - Last updated [fine tuned] determination : UT = 05h55m +/- 6 m (vs. 05h54m)


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