From: Marc Postman (postman@stsci.edu)
Date: Wed Jan 18 2006 - 07:16:41 PST
In preparation for discussion tomorrow (is the next telecon tomorrow?),
here are some predicted colors as a function of redshift and SED for
i775-z850 vs. F814W-z850 (in the AB mag system). The qualitative trends
are similar but, of course, the i-z color has quantitatively larger and
the (i775-z850) gap between z>1 galaxies and z<0.7 galaxies is also
quantitatively larger. This is important from the perspective of
isolating the red sequence in clusters without extensive redshift
information. For example, at zmag of 24, the foreground field galaxy
population has (i775-z850) colors in the range -0.1 < (i775-z850) <
0.55. This is well below where the red sequence lies for z > 1 but only
a few tenths of a mag below where the RCS lies in (I814-z850). While we
could still distinguish the RCS in (I814-z850), using (i775-z850) would
be preferable, I think.
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-------------------
Marc Postman Email: postman@stsci.edu
STScI - CMO Phone: +1-410-338-4340
3700 San Martin Drive Fax: +1-410-338-4424
Baltimore, MD 21218 U.S.A. http://www.stsci.edu/~postman
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