Chamberlin Observatory
Observatory Park
Virginia Court Elementary
Deer Trail Colorado
DAS Article on the Mercury Transit of 2006

"I set up about 20 miles East of Denver, between Bennett and Kiowa. I started shooting at 12:12 and took a shot every 15 seconds for three minutes. After that I took a shot every 10 minutes till the sun hit the mountains. Celestron C8, focal reducer, Nikon D-100, Vixen GP and Baader (white) Solar filter."
- Photo by Bryan Wilburn, DAS

At several seconds after 12:12 pm (19:19 UT), hundreds of observers across the Mountain time zone shouted as a tiny dark notch appeared in the SE limb of the Sun, not far from a large solar prominence. Some observers could even see Mercury pass over the prominence in hydrogen-alpha light slightly before first contact.  For the next four or more hours, the transit provided a stunning demonstration of the huge size of Sol, our star; the predictable physics of the planets' elliptical orbits, and the true meaning of the term "solar system."

The Mercury transit of November 8, 2006 will be remembered in Colorado for its fine weather (clear and warm), high public visibility, and excellent viewing.

This was the first transit to occur following the wide availability of inexpensive hydrogen-alpha filter telescopes, and it was fitting that the day was perfect for using those instruments, which showed incredibly sharp views of Mercury's dark side suspended above the roiling red, orange and yellow super-heated gases of the Sun's upper atmosphere (or chromosphere), fully 29 million miles beyond Mercury's orbit.

Special thanks to Mike Nelson of Channel 7, Nick Carter of 9News, Chris Parente of WB2, the Rocky Mountain News, the University of Denver, and others for helping us promote the 2006 transit viewing.

9News Weatherman Nick Carter checks out the image splitter that allowed visual and video viewing of the Sun.  Photo by Brad Gilman, DAS
University of Denver's Historic
Chamberlin Observatory
Well over 200 visitors observed the Mercury transit through the famous 20-inch Alvan Clark-Saegmuller refractor in the observatory.

The 20-in f/15 telescope was fitted with an 8-inch Baader solar filter on a square plate that extended well beyond the objective, providing shade for the finder scopes and observers.

A beam splitter designed and fabricated by DAS president Wayne Green allowed visitors to view the actual photons coming from the Sun (and the absence of photons from Mercury), while a video camera fed another image to monitors elsewhere in the observatory.


In constant operation since 1894, the Alvan Clark-Saegmuller refractor is tied with five others as the 7th largest telescope of its type in the United States.

The telescope was oriented in the "weights high' configuration to prevent viewers from having to climb too high on the observing gantry.

Photo by Ron Pearson, DAS

There was a constant stream of visitors to the observatory throughout the afternoon.

Visitors gaze up at the 28-foot-long Clark-Saegmuller Telescope (above) while they wait their turn at the eyepiece.

The first published observations associated with the great refractor were those of Dr. Herbert Howe, the first observatory director, who observed and documented the Mercury transit of November 10, 1894. See Ron Pearson's article for more historical information.

Photo by Brad Gilman, DAS

Mid-afternoon view from the balcony of Chamberlin Observatory   -Photo by Brad Gilman, DAS

Observatory Park
About 15 telescopes of  various sizes and types were set up and attended by DAS members in Observatory Park near historic Chamberlin Observatory. Herbert Howe's wife and several students observed the 1894 Mercury transit through a 6-inch Grubb refractor in the student observatory (at far right in the above photo.) The Grubb is now mounted on the 20-inch refractor in the main observatory.

"For most of the afternoon, I had a 24mm Panoptic eyepiece (120 X) on my 9 1/4-inch Celestron Schmidt-Cassegrain (full-aperture Thousand Oaks glass filter), providing a fine, close-up view of Mercury's intensely black dark side as it crept across the face of the Sun. Most of the 100 or so visitors I had were were more impressed with the views of prominences and solar surface texture through the hydrogen-alpha PST that tracked with the SCT. There were many probing questions and lively discussions, indicating that the transit was helping people see the Earth, the Sun, and the Solar System in a new way." - Darrell Dodge, DAS


The 40mm Coronado Personal Solar Telescopes (PSTs) provided an excellent view of the transit in the hydrogen alpha wavelength, despite their small size. Larger versions of the scope gave even better views, of course.

Photo by Ron Pearson, DAS

DAS member John Anderson (white hat at left) explains the operation and use of his home-built solar spectrograph, which displays the full spectrum of visible light from the Sun, showing the dark absorption lines associated with the various elements found on the Sun.

John's telescope set-up featured white, hydrogen-alpha, and calcium wave-length images. He first saw Mercury silhouetted against the Sun's chromosphere (upper "atmosphere") at 12:12:05 pm MST.

Photo by Brad Gilman, DAS


DAS member Jack Eastman's classic 6-inch Alvan Clark refractor was fabricated several years before the first Mercury transit that was viewed at Chamberlin Observatory, in 1894.

Photo by Ron Pearson, DAS


Hats were the order of the day under the totally cloudless skies. The weather was more like September than early November, with a record Denver high of 81 degrees F.

Photo by Ron Pearson, DAS


This young girl had one of the last clear views of the transit at Chamberlin Observatory as the sun began to dip behind the trees on the West side of Observatory Park about 4pm.

Photo by Ron Pearson, DAS

Virginia Court Elementary School

"The first contact was most impressive to me, and I remember how fast Mercury penetrated into the Sun. Within a few seconds one could see it surrounded by red. After that first look we spent all of our time cycling 300 children at Virginia Court Elementary School past our three white-light-filtered scopes and one hydrogen-alpha 40mm Coronado PST. - Dennis Cochran, Vic Burhans, Pauline & Cliff Ide, working with teacher Nathan Schwalen."

- Dennis Cochran, DAS

Joe Gafford's fine transit sequence shows the gradual extinction of Mercury's image (right side) as the Sun and Mercury dipped lower in the sky, increasing the negative effects of atmospheric turbulence and the volume of air and atmospheric dust and water vapor through which the event was imaged. The sun set before the transit was over in Colorado.

Deer Trail Colorado: DAS Edmund G. Kline Dark Site

"Taken at the Edmund G. Kline Dark Site with my 10" f4.5 Newtonian stopped down to 2.75" with a Thousand Oaks glass solar
filter. Olympus E-Volt-500 camera used. Composite of 52 images done in PhotoShop®"

Photo by Joe Gafford, DAS


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