From: Alex Conley (aconley@panisse.lbl.gov)
Date: Thu Dec 18 2003 - 11:59:23 PST
Do we have an email archive for discussions surrounding Serena's paper?
I don't see any mention of it in your email. If so, could you stick
my comments to Serena in there.
Alex
---------- Forwarded message ----------
Date: Thu, 18 Dec 2003 11:56:43 -0800 (PST)
From: Alex Conley <aconley@ajanta.lbl.gov>
To: serena@physto.se
Subject: new paper
Hi Serena,
Happy holidays and all that -- and don't work too much on your paper
over the break! It's an interesting paper -- it's too bad that there
are so few high-z guys for you to work with.
Anyways -- comments:
Figures:
a) It shouldn't be figure 1, figure 2, figure 3, etc., since they are
all showing the same thing and have the same caption. You should
make it figure 1, figure 1 continued, etc.
b) Why no sn1991bg in figure 1? You state that 91bg and 97cn aren't
there, but don't explain why. If this means that you cut all
subluminous objects from the data set, you should state that
more
clearly, justify it better, and eliminate the paragraph
explaining
how you estimated the error bars for 91bg. If you don't
actually
use it for anything, don't waste a bunch of space talking about
it.
K-corrections:
a) Do you have the right I band filter? First, you should give a
source
for standard Bessel I band. You probably have the transmission from
Bessel PASP 102:1181 (1990). If that is the filter curve you are
using,
you need to be aware that the normalized passbands in Table 2 are NOT
the dimensionless transmission R, but are actually lambda * R. That
is,
the filter is slightly bluer than you may think. This is not
explained
in the text of the paper.
This is something that seems to have been done incorrectly in all
previous published SCP work. The effect is not large -- if you would
like
to see the size of the difference, take a look at
http://panisse.lbl.gov/~aconley/kdiff.eps
which shows the old K-correction - the new one.
This was discovered due to a note in Jha's thesis. I ended up
emailing
Mike Bessel directly to confirm this. So you should look up Bessel
(1990), compare it to your filter curve, and if it the one you are
using
you have a (minor) problem -- but one that isn't too hard to fix.
Just divide your filter file by lambda, renormalize, and redo all your
K-corrections.
b) You say you use time information fro the B-band data. Is this
available for all of the SNe? For example, I have never found a good
lightcurve for sn1991bg with error bars in the B band.
Intrinsic Variations:
a) Don't use the word feeble. Say " a weaker correlation was found..."
instead of "a more feeble correlation". Feeble is not a formal
enough
word for a scientific paper.
b) Move the information about where you got the host extinction earlier.
It should be given right after you say that you use it and before you
give the results of your stretch fit. That is, give all of the
information about how you did your fit before you give the results.
The I-band Hubble diagram
a) You forgot the \ on a pm when you give \alpha_{I} at the beginning of
this section.
b) Figure 10: I don't know if it's possible to remove the 11 from the
y axis at the bottom of the Hubble plot. It looks like it applies to
both the Hubble diagram and the residuals, which isn't what you want.
c) What is your source for the uncorrected Hubble diagram having
sigma=0.4? That's higher than most quoted values, which are usually
more like 0.3. Phillips '99 gives 0.24 for the B band without dm15
correction.
4. High redshift supernovae
a) In figure 11 you show a redshifted I band. Redshifted to what?
Probably to 0.5, but I don't see that noted in the figure or it's
caption.
b) Did you use the I_{max} values from table 2 for the low-z SNe? I
don't
think that is a good idea because the high-z SNe were not fitted in
the
same way. I think you have little choice but to refit all of the
low-z
SNe with the template so that you treat the high and low redshift SNe
the same way. You also can't stretch or host galaxy extinction
correct
the low-z sample when combining it with the high-z sample -- it isn't
clear from the paper whether this was done or not. In general, you
have to make sure that all of the SNe that go into your cosmology fit
are treated in as similar a fashion as possible.
Alex
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