Wide Field Camera 3
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Posted by Taft Armandroff on July 06, 1999 at 14:42:40:


Dear Colleagues,

Many other astronomers and myself have been using WFPC2 to study old
stellar populations in nearby galaxies.  It is EXTREMELY IMPORTANT to
be able to place the photometry on the ground-based system in order to
be able to compare with existing photometry of comparison objects and
stellar isochrones.  The most important filters for such work, in my opinion,
are B, V & I (Kron-Cousins). My strongest advice for this important instrument are to be
able to reproduce the ground-based B, V & I systems as closely as possible.
Has any consideration been given to using the same glass B & V & interference I filters
as are used at ground-based observatories and that define the Landolt
standard system?  This would be best.  However, the outcome that is most
important is simple transformations with the smallest possible color
terms between whatever filters you end up defining as proxies for B, V & I
and ground-based BVI magnitudes.  What follows from this is that the
combination of the B,V & I response on the ground and in space are as
close as is possible.  Everything that you can do in this direction will be
immensely helpful.  As I am sure the committee is aware, some WFPC2
filters do not transform well to the ground-based system (e.g., F450W to B).

Thanks for inviting comment from the community.

Taft Armandroff