Re: Tass reference catalog

[aah@nofs.navy.mil]

So, Tom, you think that TOM1 does a better job of photometry
across the CCD than does Tycho2?  I think you will find it
hard to convince me of this.  Flatfielding is the biggest
problem for wide-field systems, so you will almost always
find systematic errors from center to edge.  Trust Tycho2
first.  I'll talk about your other suggestions in more
detail when I get back from the current trip, though Michael R.
has already done a good job of description.
Arne