Here is an analemma I generated for Las Vegas, NV of the year 2016. There is a lot of literature on this going back thousands of years. The word comes from the Greek analemma -- "prop, support". This is similar usage to the use familiar in mathematics of Lemma which as a supporting proposition. I can argue that the sundial is probably one of the first instruments devised by first man -- a simple stick in the ground whose cast shadow determines the measurement of a day. Further study by the first men, evolved into an understanding of that shadow changing with the seasons. And when the shadow is shortest separated the day from morning (AM) to afternoon (PM). Noon should be 12:00. However, it isn't. The difference is the "equation of time". And declination measures the length of the shadow. " The declination of the Sun, δ☉, is the angle between the rays of the Sun and the plane of the Earth's equator." See https://en.wikipedia.org/wiki/Position_of_the_Sun

This project is available under GNU GPL at https://github.com/str255/sun-mc
For your location edit the example parameters in equation_of_time.mc.