Re: Analyzing Data

[Patrick Wils <patrickwils@yahoo.com>]

--- Tom Droege <tdroege2@earthlink.net> wrote:
> I was just investigating why most stars found were
> below mag 
> 11 or so.   There should be more at fainter mags since there are more
> 
> fainter mag stars.  

At fainter mags, the errors are larger and since in the calculation of
the WS statistic one divides by the error, the value of WS will be
smaller for fainter stars with the same amplitude as the brighter ones.
 It is just takes more observations to arrive at higher values for
fainter stars.

> All data is not perfect.  Some nights are noisier than others.  Some 
> observation series for one night are offset from an observation
> series for 
> another night for some stars.  Other stars for the same night do not
> show 
> the same offset.  Is this a true variation or instrumental?  How do
> we tell? 

This seems to occur in other photometric studies as well, when authors
say they corrected for night to night zero-point shifts (but I am no
photometrist ...).

Patrick


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