My four-inch 1929 Alvan Clark & Sons Corporation refracting telescope
We were invited by the Mount Wilson Observatory and the Antique Telescopes Society to bring my 1929 four-inch Alvan Clark & Sons Corporation refracting telescope upon the original model number six german equatorial head and a tripod up to the Mount Wilson Observatory. This image was taken on the grounds of the Mount Wilson Observatory on Tuesday June 5th, 2012 in anticipation of the Transit of Venus.

A Herschel Wedge and two neutral density filters were used to safely darken the image of the solar disk. A 32mm eyepiece was used yielding 46.7 power for a nice image of the full solar disk with room to spare.

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Image 2844
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A small Alvan Clark telescope upon a mounting from another manufacturer
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Image 2845.

An early Alvan Clark telescope with a wood tube on the original equatorial head and tripod
This telescope dates from approximately 1857 to 1860. It is the earliest complete portable equatorially mounted Alvan Clark refractor known.

It was used to observe the Total Solar Eclipses of 1869 and 1878. There is a good chance that it was used for the Transit of Venus seen in 1874 and 1882.

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Image 2846.

An Alvan Clark refractor circa 1875
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Image 2850

Kathleen viewing the Transit of Venus through my telescope
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Image 2854.

Kathleen viewing the Transit of Venus through solar filter glasses
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Image 2855.

A projected image of the Transit
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Image 2860.

A Heliostat used to reflect an image of the sun into a large telescope
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Image 2861.

Dan with his early Alvan Clark refractor
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Image 2863.

An Alvan Clark refractor circa 1895
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Image 2871.

A projected image of the Transit
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Image 2873.

A close up of the mounting of an early Alvan Clark refractor
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Image 2878.

An original Herschel Wedge and eyepiece by Alvan Clark
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Image 2879.

A glass armonica on display
And what you may ask does a glass armonica have to do with the Transit of Venus? Well, a commemorative musical composition for the 2012 Transit was played upon this instrument.

Speaking of Transit music, were you aware that John Phillip Sousa composed the "Transit of Venus March" which is a march scored for military brass band written in 1883 to celebrate the 1882 Transit of Venus?

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Image 2881.

Another view of the glass armonica
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Image 2882.

A spectrograph
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Image 2883.

150-foot Solar Tower at Mount Wilson
Note the man in the little "Bucket" ascending the tower.

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Image 2818.

The Transit taken from the 150-foot Solar Tower
Image by Donald Lynn. This is pretty much what the Transit looked like through my telescope with a number of well defined sun spot groups. The tear drop effect was quite evident during second contact.

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The 100-inch telescope at Mount Wilson
Rumor has it that this awesome historic instrument (once the largest in the world) will be altered to allow for viewing through an eyepiece and then you can rent some observing session time on it. That would be spectacular! Originally, this telescope was intended to be used as a camera or with a spectrograph.

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Image 2828.

The 60-inch telescope at Mount Wilson
We had some amazing images of Saturn through this historic instrument. You can rent either a full evening or a half evening observing session on the 60-inch telescope. Originally, this telescope was intended to be used as a camera or with a spectrograph. Optically, the 60-inch telescope was a prototype for the later 100-inch telescope.

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Image 2838.

Rendering of a 3-D computer generated model of my 1929 Alvan Clark & Sons telescope upon the original permanent pier
Select the image to see additional renderings of the 3-D model of my telescope generated using the Autodesk ® Revit ® Architecture software.

Transit of Venus 2012 overview
These images were taken during the Transit of Venus across the sun event from the grounds of the Mount Wilson Observatory above Los Angeles in Southern California on Tuesday June 5, 2012. We were invited by the Mount Wilson Observatory and the Antique Telescope Society (ATS) to bring my 1929 Alvan Clark & Sons Corporation refracting telescope to this event. The telescopes on display were from members of the ATS and from local amateur astronomers. There were a number of lectures, tours, and viewing sessions hosted by the ATS associated with the 2012 Transit of Venus event. We enjoyed a viewing session with the 60-inch telescope (Saturn was very impressive!) and we had dinner within the dome of the 100-inch telescope and tours of the CHARA array and the 150-foot solar tower.

A Herschel Wedge was used to safely view the solar disk. The wedge allows about 4.6% of the light that passes through one of the prism faces to be reflected toward an eyepiece. 95.4% of the light and heat goes into the prism and exits through the other face and out the rear of the housing, dispensing the excess light and heat. Herschel Wedges are also referred to as "Tie Burners" due to the excess light and heat emitted through the back of the unit. While a Herschel Wedge greatly decreases the intensity of the light, they do not affect the visible spectra, resulting in a more accurate spectral profile thereby yielding a true "White Light" image. Two neutral density filters screwed into the eyepiece further darkens the image for comfortable viewing. A 32mm eyepiece yielding 47.6 magnification was used to view the Transit. This low power was selected so that the entire solar disk and additional space around the solar disk could be seen at one time in the eyepiece.

A s h e l f o r d -C o n s u l t i n g
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Luis Ashelford | Architectural Designer
1711 Perkins Lane
Redondo Beach, CA 90278

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