"Bjorn Damm" <bjornd@mail.invalid> wrote in message news:euA8d.159$fQ5.22@amstwist00...

"Rob Dekker" <rob@verific.com> skrev i meddelandet
news:Uqu8d.24335$QJ3.14580@newssvr21.news.prodigy.com...

...

So, to answer the question : The target range for ET transmissions,
detectable at seti@home at 100LYs would be the following :

It's probably a bit optimistic expecting ET to be within 100 LY.

The Hiparcos catalog lists 2473 stars within 100.1 LY (32.5 mas) If the
stars last 10 billion years and a technical civilisation evolve on planets
around all of them, the technical civilisation has to last 4 million years
if one should always be detectable.

Maybee you should assume a distance of 1000-5000 LY.

...

1000LYs should indeed give a much larger audience..:)
How many stars are there withing 1000LY's ? About a million or so ?

Any way, the only application that would be detectable at that distance
would be narrowband radar, with a target range of 1.7 light minutes or more :

    - factor (1000LYs / 300) / 1M = 1.7 Light-minutes = 3*10^7 km. for
narrowband radar.

That would probably just be asteroid radar....
Unless an ETI spends a significant amount of energy (proportional to their
overall energy usage) on some form of asteroid radar, we will not hear very much
from 1000LYs away...:(