Last Light at the Big Ear

In 1997, the famed Big Ear,
the Ohio State University Radio Observatory,
was bulldozed to make another
#@#$%^&*  Golf Course

This had been a Radiotelescope that the OSU football team could be proud of.

Microwave Update '97 was in Sandusky, Ohio.
We were able to tear ourselves away from the nightlife
for a tour of the Big Ear.  It had ceased operation
two weeks before.  Here is the chart recorder trace
of the last source observed:

"First light" for a telescope is a time for celebration.
This was a sad occasion.

Here is how the Big Ear looked in greener days:

Designed by Professor John Kraus, W8JK, this antenna configuration is now referred to as a Kraus radiotelescope.  The fixed parabolic reflector, on the left, focuses the beam on the flat reflector on the right.  The flat reflector tilts to adjust the elevation (declination, if you are an astronomer) of the beam.  The azimuth is fixed and sweeps (in right ascension) with the rotation of the earth, so one slice of sky is scanned every 24 hours.  The area between the reflectors is flat and covered with aluminum plates to reduce noise from the warm earth.
The feed horn is designed to take advantage of the image reflection produced by the plates, effectively doubling the aperture of the parabola.

Notice that the antenna is like my Periscope Antenna but lying flat, and much bigger.

See for some history of the Big Ear, or the book Big Ear, by John Kraus, for details.  Here is a picture of Professor John Kraus at the dedication of the historical marker in 1998

SETI League photos, used by permission

Pictures at the wake of the Big Ear
by Bob Templin, W8ZSX (now W5OE), shown here standing in front of the antenna

Parabolic Reflector

Flat tilting reflector, from behind, showing tilt adjusters for the flat reflector - aligned with an optical system

Flat plates between reflectors - the image of the reflector reflected in the plates makes the effective aperture twice as large

Feed horns - two feed horns to produce two beams separated by a few seconds.
The background noise from each beam is subtracted from the other.  A radio source travels through one beam, then the other, producing sequential positive and negative traces on the chart recorder, while stray interference appears in both receivers simultaneously.  Each feedhorn is a vertical stack of two rectangular horns with internal lens plates and curved screens around the aperture to reduce sidelobes.

Feed trolley was added more recently, for SETI searches.  If a SETI was ever found, it could be tracked by moving the feed trolley.

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