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From: mangoe@umcp-cs.UUCP (Charley Wingate)
Newsgroups: net.sf-lovers,net.astro
Subject: Re: visible civilization (real sources)
Message-ID: <1128@umcp-cs.UUCP>
Date: Tue, 6-Aug-85 20:44:06 EDT
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Posted: Tue Aug  6 20:44:06 1985
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[followups to net.astro, please]

I knew I had sources somewhere....

In the May 1975 _Scientific American_ there is a nice article on searching
for extraterrestrial intelligence by Sagan and Drake.  A summary of their
articles (or parts of it anyway):

Arecibo Observatory, when transmitting, is at least a million times brighter
than the sun.  This signal can be detected by a similar receiver at a
distance of about ten thousand light years.  A number of other sites have
similar capabilities.

In the FM and VHF tv bands, the earth is quite bright.  A receiver system to
detect such signals was conceived of at the time of the article, to be called
'Cyclops'.  Employing 1500 antennas of 100 meters each,it would be able to 
detect such signals out to several hundred lightyears.  Such a system would
not be beyond our current technology-- but it would be very expensive (~$10G).

These observations do not rely on resolving the earth as a separate body.

C Wingate