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Edit: Getting the exact value winds up being simple, but it was only later in the day that the answer occurred to me. All we need to do is ask for the altitude and azimuth of the Ecliptic’s south pole! The ecliptic itself will be highest above our horizon in exactly that direction, at an altitude that is exactly 90° above its pole. Thus the answer is given ...

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By inspection of a star charting app, I'd say the circles lie in the celestial equator, ie declination equal 0 degrees. Stars above the circles are to the north and vice versa.

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The equator (Earth's rotation plane) and ecliptic (Earth's solar orbit plane) cross at the vernal equinox ♈, the zero point of both right ascension and ecliptic longitude. Relative to the ecliptic, the Earth's north pole is tilted toward ecliptic longitude λ=90°, where the Sun appears at the June solstice. Constellations in that general direction are highest ...

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Maps of the sky are being used to actually get to know the sky. Thus you take the map and hold it above your head (as opposed to a map of the Earth's surface where you look down on Earth). Thus East and West are switched between that two types of maps, so that directions match actual directions when viewing the map.

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Have a look at https://www.pveducation.org, specifically section 2.4 on Terrestrial Solar Radiation. It describes the equations required and has some online calculators and interactive plots. If you wish to calculate in your own code, I'd recommend the pysolar Python package: https://pysolar.readthedocs.io/en/latest/. It has methods for taking the latitude, ...

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What I think you're trying to do is workable, but approximate. You first find the Sun's geographical position (GP), the point on the Earth where the Sun is in zenith at the time of the observation. You start by finding the Sun's GP latitude (its declination). It's approximately 23 degrees times the sine of ((days since the vernal equinox)times 360/365). Then ...

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Heliocentric longitude is a direction, not a date. A Heliocentric longitude of 0 is the direction from the sun towards the vernal equinox (currently in Pices) You can ask for the date on which the Earth is at a particular Heliocentric longitude. A careful calculation would require accounting for the eccentricity of the Earth's orbit, and also adjusting for ...

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Both comments are perfectly valid. For clarity I would describe it this way, now that I understand it. You have to imagine being inside the celestial sphere look outwards. From within the sphere you have (counter-clockwise, starting at the top) North, East, South and West. But if you view the sphere from the outside then of course East and West are swapped. ...

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This answer supplements the other, better, clearer answers here already. Why does the Sun track out a seemingly sinusoidal path on the celestial sphere? It seems to be sinusoidal because for low inclinations the shape is roughly to sinusoidal (straight when crossing zero, has gently curved and symmetric extrema) and so we don't stop and ask what shape it ...

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The earth is smoothly and constantly moving around the sun. At the moment of the equinox, a line from the center of the sun to the center of the earth passes through the equator. That only lasts an instant. Before that instant, the line is on one side of the tilted equator, and after that, it's on the other side. The day labeled "the equinox" is ...

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