Re: Saturation Improvements

[Herb Johnson <hjohnson@pluto.njcc.com>]

I appreciate there is a debate about how to use saturated star images. But
PLEASE note this begs the question, namely how did Tom - and how will
other TASS members and the software they write - determine a QUANTATIVE
value for saturation? Chris suggests, in effect, that you eyeball the
flattops of the pixel images; or you look at a histogram. That was not
very quantative or methodological, the "messy details" he waived off were
in fact what I was asking about! 

As Tom's reply confirmed there is some nonlinear behavior "near"
saturation, I believe it is reasonable to continue one ad-hoc method of
setting a maximum ADU count for the "peak" pixel as saturation, and 
cutting off stars which are "near" that level; and then to use the
aperture photometry methods of some of our data reduction programs.

But I'd rather DIFFER discussion of what to do with a saturation value and
work on how to DETERMINE saturation in a quantative, procedural way; so
our software (or eyeball if it comes to that) knows what to do. Also,
a discussion will record what we DID do, so that in the future when we or
someone reviews or revises our data, the criteria for saturation will be
clear.

 Herb Johnson

Herbert R. Johnson              http://pluto.njcc.com/~hjohnson
hjohnson@pluto.njcc.com         voice 609-771-1503, New Jersey USA

             amateur astronomer and astro-tour guide
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