From: Alex Conley (aconley@panisse.lbl.gov)
Date: Tue Mar 09 2004 - 16:24:57 PST
Hmm, I'm not actually sure what the name of the archive is.
Anyways, Tony asked me to look into this K-correction issue between
you and Lifan. Since I don't know precisely what it is that Lifan does
to calculate K-corrections, I can't perfectly stand in for him, but
perhaps I can add another calculation to the mix.
I should preface this by saying that I have issues believing any
K-corrections involving rest frame I band because of the Calcium
feature.
I don't think that the uberspectrum approach is well suited to something
that varies so significantly between different SNe. The idea behind
Lifan's approach (matching SNe to actual spectra) is probably a better
way
to handle it, BUT you have to do a good job choosing your matching
spectra. And that is the part of Lifan's K-corrections that I don't
understand, so I can't judge his relative to yours.
My K-corrections are based on Rob Knop's Uberspectrum, but are a little
simpler. I don't use Rob's color based spline warping technique, but
the
simplier one advocated by Nugent et al. 2002, which is based on a
galactic
reddening law. So what I would like to do is calculate some
K-corrections
for comparison with yours, and to do that I need to clarify what you
have
done slightly in your recent email on the subject.
First, when you give K-corrections as a function of date, do you mean
observer or rest frame date?
Second, what are your filters really? Do you mean Bessell I band for
both? Or one of the others (Cousins, etc.).
Both of these are probably small issues, so I will proceed on the
assumption that you mean observer frame + Bessell I band.
Alex
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