[Aavso-photometry] Sources of accuracy and precision in photometric measurements

[Justin Pryzby]

On Thu, Dec 15, 2005 at 12:10:07AM +0200, Radu Corlan wrote:
> > There are 4 main areas which affect doing accurate, high-precision 
> > photometry:
> > 
> > 1) the sky background estimate

> > 1. Sky estimation:
> > Mira offers 3 methods: Mean, Median, and Mode. Knowledgeable photometrists 

> Mode does have good outlier-rejection properties. There is however one 

I just wanted to add that, no matter what algorithm you use, it is
probably critical to use the statistical combination of multiple
pixels.  Average+rejection does this, of course, but the textbook
definition of median and mode do not.

For a "mode" algorithm, what you want isn't "the most frequent value",
but something to the effect of "the weighted average of the values
within some small range of the most frequent value, possibly computed
iteratively", and for "median" something like "the weighted average of
the values within some small range of the the center pixel value,
counting duplicities, possibly computed iteratively".

-- 
Clear skies,
Justin