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Re: Soliciting criticism



Michael and all,

Is the singularity at the pole a particular problem?  For example, what 
will DS9 do when I give it a field who's center is at +90?  I will try this 
as soon as I get some data.  ;^)

Otherwise, this would seem like a useful thing to do for test data.  I 
should be able to get a lot of coverage (many measurements) for a small 
area.  Some stars will be followed all night, and as Michael says, with 
constant air mass.  This is also as far away as one can get from the moon 
so it is a good moonlight night project.

Tom Droege

At 06:04 PM 11/5/01 -0500, you wrote:

>   Robert wrote:
>
> > I'm hoping some of you have the desire to critique, and offer suggestion
> > about the graphs here: http://robertcreager.mystarband.net/ .  The are all
> > from Tom's data, night 2157 (from a few weeks ago).  As the graph titles
> > imply, one is reduced from source extractor, and one from sps2x.
>
>   It puzzles me that the two graphs are so different.  In one case,
>the I-band data appear to have smaller scatter at a given magnitude;
>in the other, the V-band data.  I would guess that there are significant
>tweaks you can make to the parameters which control the software.
>In theory, one might expect the same results from two programs running
>on the same data, no?
>
>   I'm afraid I'm not familiar with either program, so I can't
>suggest which parameters you might change, and how much.  Sorry.
>
>   Here are my suggestions:
>
>      - try to figure out why one piece of software does better on
>              the V-band, and the other on the I-band.
>              Perhaps one camera has sharper images, and one
>              program's parameters turn out to work better on sharp
>              images?
>
>      - pick one set of results, both V and I.  For stars with >= 20
>              measurements, calculate the Welch-Stetson statistic.
>              Select those stars with very large values of this
>              statistic, and make some light curves.  Some of the
>              chosen stars will be contaminated by single bad
>              measurements -- ignore them.  Try to come up with
>              a way to pick out the stars which really do vary more
>              than they ought to.  Then look:
>
>                   trends versus position on chip?
>                   trends versus color?
>                   any matches to catalogs of known variable stars
>                           in the area?
>
>   That's what I'd do.
>
>                                                 Michael
>