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Joseph Gruber

Thoughts from a spacecraft engineering manager, photographer, coffee aficionado, and future Mars resident.

DC Analemma - Week 1 (or Attempt 1!)

Today marked week one of my attempt to shoot (digitally) an analemma in the Washington, DC area! Or I should say attempt one as I wanted to start last week but the wintry weather delayed the start until this weekend. I can hear you asking though - what is an analemma

Analemma of the Sun
Analemma of the Sun by György Soponyai is licensed under CC BY-NC 2.0

Simply put, an analemma is the figure-8 curve that the sun traces across the sky when viewed at the same time of day throughout an Earth year. This is caused by both Earth’s tilt and it’s elliptical orbit around the Sun. But it’s not only restricted to Earth as an analemma can be observed on other celestial bodies, including Mars!

I don’t quite remember what peaked my interest in capturing an analemma over the DC skyline but a few weeks ago my interest started to peak and I began planning this year-long project. If I was going to capture this astronomical sight in the DC area however, I knew it had to include one of those gorgeous views of DC you often see.

Since I’ll be capturing the analemma digitally, I can use the power of Photoshop to create a composite photo from multiple exposures. A “classic” analemma, including the first ever analemma photo captured, would utilize a single piece of film over the course of a year. Since I’ll be creating a composite photo though I’ll be able to create a base exposure for the foreground and then use my solar filter for the Sun itself, as seen above.

The good thing about an analemma is that the Sun’s position in the sky is pretty predictable. As you’ve likely heard since you were a kid, the sun rises in the east and sets in the west. But not quite, as again due to Earth’s tilt and orbit, the Sun moves in the sky throughout the year from the east to the southeast before starting the trip back to the east again.

Knowing this, I began looking at Google Maps to figure out a “classic DC” view when I remembered that the Washington Monument is a pretty good compass. And there’s a view from Rosslyn, Virginia looking straight to the east with a sweeping vista to the southeast that includes not only the Washington Monument but also the Capitol Rotunda and Lincoln Memorial. Which brings us to today when I went out to start this 52-week long project.

While setting up to capture the first frame of the analemma, I quickly realized that my location choice and the time of day I chose - 9AM Eastern Standard Time - was not going to work. While the view of the Lincoln Memorial, Washington Monument, and Capitol Rotunda are beautiful from this location, it’s only when zoomed in due to distance, greatly reducing my vertical field of view for the analemma. The location I was shooting from was also higher than the monuments causing additional issues with the vertical field of view based upon the time of day I had chosen with the Sun ranging from 47° at it’s peak in the summer to 14° at it’s minimum in the winter.

So back to the drawing board. I’ve already decided to move the time back one hour which will reduce the maximum vertical to 35° and the minimum to 5°. Now the hard part, finding a new location. I already have a couple of ideas in mind and planning to check one out tomorrow morning. If all works well this time next year I’ll have a great photo to share!

Attempt 2 Update: This should do just fine! (Note, this is only a rough draft of the first shot of 52)

Sun over the Tidal Basin in Washington, DC