A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Tony Oz
Date: 2018 Mar 13, 03:31 -0700
Dear Sean and Gary,
Thank you for the feedback.
I should have made the translation myself. The nomogram is called "A celestial body's rise and set semi-circular true azimuth".
The left wing of the parabola has the "Latitude of observer" label, the vertical scale has the "Declination of celestial body", the right parabola's wind has the "Rise (set) azimuth if same-name φ and δ" label on the inner side and the "Rise (set) azimuth if contrary-name φ and δ" label on the outer side.
The comment below the nomogram is "When observing from the sea level - the center of the celestial body is on the plane of horizon if: - Sun's lower limb is over the horizon at 0,7 of its diameter; - Moon's upper limb is at altitude ~0°; a star or a planet is at 0,5° altitude (a Sun's diameter)".
The rest of the text is translated correctly.
So, back to my initial questions.
I wonder why the nomogram is based on the parabola?
I wonder how could I re-calculate positions of each and every angular mark along each scale?