Data Cleaning

["Thomas Droege" <tdroege2@earthlink.net>]

The weather looks awful for the near future so I am trying schemes to clean
the data.

It appears that it is possible to improve the data by cleaning it by a
relatively simple and unbiased (I hope) cut.

The result is not that the data looks much better on a sigma mag plot, but
that it is easier to pick out the variables if there are not so many
"outliers".

Progress is being made.  The present plan puts a number in the V flag
position that contains the fraction of "bad" points in the image that
contains the particular measurement.  How can one tell a bad point?  Well
it is not possible to detect a single bad point.  One can only pick out
points that are away from the norm for a particular star.  One expects a
small fraction of points away from the mean in an image because some stars
are variable.  However images with a large fraction of their measurements
away from the mean are probably "bad" while images with a small fraction
are probably "good".  Putting the fraction of bad points in all the data
lines allows a user of the data to set his own cut.  

Stay tuned, boys and girls, for the first time I am making progress in
"cleaning" the data.

Tom Droege