Saturday, May 06, 2006

The old telescope maintenance routine -- a Carl Bamberg transit

I spent today trying to do all of the maintenance work at the Ryerson Observatory that has been long-delayed by lack of time. We generally hold these "work days" once an academic quarter.

One of things we decided to do was to move our Carl Bamberg transit telescope down to the office to decide on cleaning and to see if we can put it out on display somewhere. It's a historical instrument, being the first transit at Yerkes Observatory and on campus here at the University of Chicago for over a hundred years. It's not in use and suffers a harsh life in a box on the roof.

Transit telescopes are meticulously aligned to the meridian (a line running north-south) and are designed to measure the exact moment a known star crosses that line. When that happens, the stellar time is exactly the Right Ascension coordinate of that star. Once you have the stellar (or sidereal) time, it's easy to convert into solar time. This was the premier method of accurate time measurements until atomic clocks appeared. The one we have is called a broken transit because the light is bent 90 degrees in the middle of the instrument. It is also known as a geodetic transit.

Inscribed on the brass objective lens assembly is "Carl Bamberg Friedenau No. 1300."

Also noted, after hearing falcon cries for two days in a row, was I discovered that we are hosting a peregrine falcon's nest just below our office windows. They didn't pick the best of sites: it's in a rain gutter. I wonder if I can get a non-obtrusive webcam pointed at them.

I see the Smithsonian also has a Bamberg transit.

Somebody in Germany has one too (slow link).

Instructions on running University of Washington's transit is here.

And let it be known, any proper Scientific Instrument should be made of brass and green felt.

UPDATE: After looking a NMAH Geodetic Transit, I think the filar micrometer floating around the office could be originally from the transit. Look at the right side of the transit in the image.

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