From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Sat Apr 12 2003 - 16:44:23 PDT
Hi Rob,
You raise several issues in your reply. Let me concentrate on just
one for the moment. You said
> The way I estimate E(B-V) is not by subtracting observed B-V from an
> intrinsic B-V, but rather by figuring out what E(B-V) I need to process
> the appropriate stretch spectrum through (in addition to redshifting it
> and then putting it through Milky Way extinction) in order to get the
> observed integrated R-I color. E(B-V) is as such a perhaps better
> thought of as a parameter ...
But, on page 14 of the paper, in the last paragraph you say "... and the
host galaxy E(B-V) (measured from the peak color of the lightcurve)."
In the preceding paragraph on that same page you say "... a template
spectrum ... for each day ... must be modified ... to reflect dust
extinction ... Reddening effects from dust were calculated given the
E(B-V) parameter (measured from the lightcurve fits) (sic) for the host
galaxy."
To me the first says you are using the peak color to get E(B-V) and the
other says you have a E(B-V) parameter that is used to correct the
template at *all* lightcurve epochs. If you are using E(B-V) as a
parameter for all the lightcurve epochs, then the dispersion in U-B
must affect all the lightcurve points. This will affect the stretch as
well, and we don't even know whether that hurts or may even help.
Doesn't that mean that in your approach you can't do anything that is
self consistent in treating the intrinsic color dispersion given the
current state of knowledge? If so, then I would advocate letting the
scatter of our own U-contaminated SNe tell us what intrinsic dispersion
to use for the final Hubble-diagram points.
I apologize in advance if I'm still not understanding something here.
In part I am testing whether the paper is telling the reader how the
analysis was done.
- Greg
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