The Sogn Valley Radio Astronomy Observatory
Joel Weisberg
Carleton College Department of Physics and Astronomy

Founding the Sogn Valley Radio Astronomy Observatory

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Several Carleton students and I built a radiotelescope, whose construction was described in a series of articles by George Swenson in Sky and Telescope magazine. It was an extremely difficult project, but after several years of work, we eventually succeeded.

The telescope was a two-element 73.8 MHz interferometer, a (very) miniature version of current professional interferometers such as the Very Large Array in New Mexico.


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Fig 1: Early tests near Goodsell Observatory



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Fig. 2: Setting up antennas near Lyman Lake



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Fig 3: Waiting for results at Lyman Lake.


After these attempts to observe from the Carleton campus, we decided that there was too much interference from local and Twin Cities TV and radio stations. Consequently, we moved our observing site to Mac and Margaret McCutcheon's farm in the Sogn River Valley, about fifteen miles southeast of Carleton. The Sogn Valley shielded us from the radio interference that dogged us at Carleton, and we were able to successfully observe the Sun and the Cygnus A radio galaxy from this site.



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Fig. 4: Setup in the Sogn Valley



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Fig. 5: Ready to go at the Sogn Valley



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Fig 6: Results!



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Fig 7: More Results: Cygnus A 

Cygnus A
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Fig 8: Cygnus A
(Image courtesy of NRAO/AUI)


It is remarkable to contemplate the immense rate of advance of technology represented by this telescope. Cygnus A was only discovered by professionals in the late 40's. By the mid-80's, it could be observed by our amateur equipment (albeit crudely). It took many years before its true nature was recognized -- it is a pair of enormous (larger than a galaxy in size) lobes of radio-emitting gas that was probably ejected as it attempted to fall into a too-engorged supermassive black hole at the center of the galaxy. Radio images from the Very Large Array show beautiful, detailed structure in the lobes.

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Last updated on July 27, 2005.