Re: 3 out of 6

From: Christian Ackermann (
Date: Fri Apr 28 2000 - 18:50:38 PDT

  • Next message: "Re: 3 out of 6"

    > ... what is the limit (approximate magnitude) that still can be
    > > seen without any binocular or telescope?
    Jay Respler wrote:
    > It's exactly the same as looking at the stars. Whatever your stellar mag limit
    > is, it is the same for sats.
    I don't think it's the same. Photo receptors in the retina have to be hit 
    by a minimum amount of photons per second to yield a perceptible 
    output to the brain. If you look at a star at the magnitude limit its light 
    will concentrate on one spot of the retina. An equally bright (fast 
    moving) satellite will not be visible because its light does not stimulate 
    an individual receptor long enough. Of course you might succeed to 
    exactly follow the satellite with your eyes but I can't imaginge that 
    this works precisely enough.
    Christian Ackermann
    185 m
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