Two of the above activities have made use of the equation of time but how is it determined? It is one of the things done in the Astronomical League’s Analemma Program. To see how it is done find a telephone pole, street light, other tall straight object, projection on your house, or drive a pole into the ground. You just found a gnomon. Go out weekly for a month or two at exactly the same time of day (Standard Time) and note where the sun casts the shadow of the tip of your gnomon. If possible place a mark for reference so you can see all your points at once. You’ll find the shadow will move the most between observations if you are working in the spring or fall. Graph your results with days (x) and the shadow’s distance from your gnomon (y). Do it for a year and you will get a graph that resembles the picture. Consider following the better instructions on the Astronomical League’s Analemma page and completing the program there.
I completed the Analemma Observing Program on October 3, 2017. Due to an erroneous assumption, I repeated the observations for a second year. See my original Analemma Observing Program results by clicking here.
Here is my Gnome and recording table I used
From my Analemma results, the observations for the Equation of Time are here.
A larger view of my Equation of Time is:
