Hi, all

I wanted to let you know of the current status of BRG selection testing.

I implemented the suggested two-equation approach to photometric 
redshifts. It worked much better... but even better was using
the g-r-i equation for every object. This is reflection of the
photometric z polynomial's sensitivity to measurement error.

The current selection code finds 7 objects in roughly a 2 sq-degree
field. Most of these are spurious targets, either due to saturation
effects or measurement error.

Here are the areas that I believe require attention:
	photometric redshifts: we need to be able to calculate the
		photometric-z taking into account measurement errors.
		Andy Connolly has volunteered for this.

	K-corrections: the current code uses linear interpolation
		between 5 points from a table of Frei and Gunn 1994.
		This is probably not sufficent.

	real parameters: we are currently cutting at (g-r)=1.4
		and M_r = -22. These numbers need to be better defined.
		I believe the idea is 1-sigma redward of the mean BCE
		color, and 1 magnitude fainter than M_r_star.
		Francisco and Bob, weren't you looking into this?

	a surface brightness cut: do we need one? more to the point,
		do we wish to duplicate the galaxy selection criteria
		with looser cuts, and then apply BRG cuts?
		Michael, Neta, and Marc, do you want to think about this?

	should we use 3" aperture magnitudes for colors instead of
		Petrosian mags? (I am beginning to think so.)
		Further testing with the data and selection code
		can shed light on this.

	further testing: there are many hanging questions left to
		explore. for instance, why are there objects just
		above the cut lines but not selected in the plot
		I show on the BRG web page?

Our current group of volunteers is Neta Bahcall, Francisco Castander, 
Andy Connolly, Bob Nichol, Marc Postman, and Michael Strauss.
My attention will be elsewhere next week, so others will have to
run the code and look at the output. I think Michael is gearing up
to, and Bob and Francisco are in position to. I certainly think we
should keep the momentum up until the meeting Nov 14.

Detail about the current state of affairs can be found at 
http://www-sdss.fnal.gov:8000/~annis/sdss/BRG.html.

Jim