Nightscapes - Robert Arn
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Geometer's Playground

Featured on NASA's APOD (Astronomy Picture of the Day) June 6th, 2011.

Imagine if you will, a sphere that has been cut in half. You are now standing in the center of the cut side. As you look out you see a pyramid lying on the ground, concentric circles in mid-air and an arch on the inside of a sphere. What a sight to see! So to capture this exquisite view you take a cylindrical camera lens and take images as you rotate the camera all around the inside of the sphere. Then take the two dimensional cylindrical images and turn them into rectangles, attach them to each other and you get the image above - a Geometer's Playground!

The Ames Monument, located near Buford, WY, is a tribute to Oakes Ames and Oliver Ames, Jr., Union Pacific Railroad financiers. Once the railroad was complete this monument was built to honor the brothers. At the time, it marked the highest point on the transcontinental railroad at 8247ft (2514m), however years later the railroad tracks were relocated further south. Nowadays, this monument stands alone, several miles from the interstate and several miles from any other structure. On July 24th, 1972 the Ames Monument was added to the U.S. National Register of Historic Places.

There are many fun astronomical happenings in this mosaic. Moving from left (West) to right (clockwise) we see the moon setting. Covered by light clouds in different parts of the atmosphere makes light from the moon reflect and diffract causing a spectacular lunar halo and lunar corona. As we begin to look to the north-east we see the Milky Way, our own galaxy, start to rise and arch over the Ames Monument. Directly to the right of the pyramid near the horizon are lights from the city of Cheyenne.

This is my most technical nightscape to date and it falls in the newly created category of "Time-Lapse High Dynamic Range Mosaic". Normally, taking the frames to be used in an image is the easy part, compared to processing. However with so many things going on in this image, capturing the data in this case was quite difficult. I started when the moon was as you see it, several degrees above the horizon. I quickly captured the lunar halo, followed by the lunar corona, then with a fisheye lens I recorded the landscape in eight pieces. Soon after that was complete and the moon had set, I did another pass of eight frames to record the background sky, including the Milky Way. However a quick one minute image did not record enough detail of the Milky Way so using the Astrotrac and a 20mm rectilinear lens, I captured the Milky Way in six pieces. A few hours on the computer afterwards and the final product is what you see above a full 360x172 degree view.

Location: Ames Memorial Pyramid, Near Laramie, Wyoming
Date: 2011-05-10
Camera: Canon XSi (modified)
Lens: Sigma 10mm f/2.8 Fisheye, Sigma 20mm f/1.8, Canon 50mm f/1.4
Mount: Still Tripod, Astrotrac
Landscape: 8x60 seconds 10mm f/2.8 ISO 1600 (Mosaic) (Still)
Background Sky: 8x60 seconds 10mm f/2.8 ISO 1600 (Mosaic) (Still)
Milky Way: 6x600 seconds 20mm f/4 ISO 800 (Mosaic) (Astrotrac)
Lunar Halo: 1x2 seconds 10mm f/2.8 ISO 200 (Still)
Lunar Corona: 1x4 seconds 1x0.6 seconds 1x1/3200th seconds 50mm f/4 ISO 400 (Still)
Processing: PTGUI Pro, Photoshop CS5, Topaz DeNoise 5