Re: Ensemble analysis: "new variables"

[Tom Droege <tdroege2@earthlink.net>]

Is this not a multi-stage process?  One also has to eliminate the variable 
stars from the Tycho catalog.  I assume that there are some that are not 
(yet) known to be variable.

Tom Droege

At 06:09 PM 1/30/02 -0500, you wrote:

>   Let me second Arne's note that one must be careful not to
>pick saturated stars as input to an ensemble average.
>Andrew, if you have already matched up the TASS stars
>to the Tycho catalog, let me recommend that you simply
>choose stars within a "sweet spot" of magnitude: for example,
>stars with 9 < V < 10, and 9 < I < 10.  Your numbers will
>probably be different, but I hope you see what I mean.
>
>   In fact, you can pre-process the Tycho catalog in the area
>of a particular image, and pick out the good ensemble stars in advance.
>You might even make up a separate catalog of "good" Tycho stars
>for this use...
>
>                                       Michael