42 degrees, 58 minutes, 43.945 seconds North = 42.979429166666667 degrees North (precise latitude of this wall at SC4)

23 degrees, 26 minutes, 22 seconds North = 23.439444444444444 degrees North (precise latitude of the Tropic of Cancer)

42.979429166666667 minus 23.439444444444444 equals 19.539984722222223 (precise elevation of the sun on June 21st at SC4)

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19.539984722222223 + 23.439444444444444 + 23.439444444444444 = 66.418873611111111

90 minus 66.418873611111111 = 23.581126388888889

Based on these calculations, the elevation of the sun on December 21st would be 23.581126388888889 degrees above the south horizon at SC4. This differs from the NOAA Solar Position Calculator figure of 23.62 degrees.