From: Marc Postman (postman@stsci.edu)
Date: Thu Jan 05 2006 - 15:16:48 PST
Lori, Saul,
Here is a plot that nicely shows the improvement HST brings to galaxy
photometry for hi-z clusters. The plot is for RXJ1252. The ground-based
data is from VLT (Rosati, Franx). While I don't have precisely the same
filters from VLT, they're close enough to be a reasonable comparison.
The open circles are non-members. The closed black circles are members
(either by spec-z or photo-z). The red circles are the early type
cluster members (either by spec-z or photo-z and with visual
classifications from ACS inspection). You would be hard pressed to
identify the red sequence in the ground based data but it whacks you in
the eye with HST quality photometry.
I think this figure or one like it will make the case for the second
color with HST.
Marc
On Jan 5, 2006, at 2:47 PM, Lori Lubin wrote:
> Hi Marc,
>
> We discussed your plot on the telecon this morning. They are
> considering doing the same clusters in another band F775 for Cycle 15.
> Saul would like a space versus ground-based CMD comparison for one of
> the target clusters to show how much better the space-based data would
> be for the galaxy/cluster analyses (ala Blakeslee). Do you have these
> kinds of data for one of the higher z GTO clusters that are in the SN
> sample. We can make one for CL1604 but it would be more telling for
> the higher z targets.
>
> Thanks.
>
> Lori
>
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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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