RE: ATM Puzzled about the limiting magnitude of the eye.....

[Andy Saulietis <iss@pvtnetworks.net>]

Mel writes,

>Yes, the contrast between star and background is critical.  What happens
as the test stars become
>fainter and fainter is that the visibility goes from 100% down to 50% down
to whatever level you
>dare claim as 'detectable'.  I like the criteria that the star must be
visible for three separate
>times during a 5 minute stretch.

We used the Tiffany visibility data at NASA to predict whether
human observers could see a particular target
size/brightness/background/adaptation
combination. The data came from WW2 in an effort to see at what ranges
aircraft could be seen and was extended to include point sources
with dark backgrounds.

Visibility is a gaussian probability function in
terms of one, two, or 3 sigma certainty of detection
using double blind data.

The Tiffany data was completely empirical, the subjects
were mostly female. The PI was Arthur C. Hardy, my
faculty adcvisor in the early 60's at MIT.

I don't have the original papers available for
these studies, maybe they're on the web by now.


  

Andy Saulietis
ISS Enterprises
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