From: Serena Nobili (serena@lpnhep.in2p3.fr)
Date: Tue Oct 05 2004 - 03:13:41 PDT
Hi Greg,
just a quick comment.
On Tue, 5 Oct 2004, Serena Nobili wrote:
> c) I would like to see extinction applied for the I-band Hubble diagram.
> 99ff has extinction, as the later analysis shows, and 99Q might have
> extinction (depending on how all the photometry works out).
> For instance, for 99Q Vitaliy measures E(B-V)_Host = 0.095+-0.051, and
> if he uses a time of max constrained to that given by Tonry, he gets
> E(B-V)_Host = 0.200 +- 0.038. (My opinion is that applying Tonry's
> constraint to our fit seems unnecessary now.) This extinction-corrected
> Hubble diagram should be one of the comparisons shown in Fig 12.
> (The statment in the text that these SN do not have extinction should
> be modified, as that is based on the analysis of others which
> apparently is inconsistent with our own).
>
according to the most recent email by Vitaliy in the paper archive:
http://panisse.lbl.gov/collab/archive/iband/0150.html
the extinction given by SNminuit is ~ 0.02 +-0.05 in the case
tmax is not constrained, and not 0.095 as you say. Am I missing a more
recent result?
Interestingly, if E(B-V)~0.20 mag one would get E(B-I)~0.4 mag,
equal to the effect expected in case Chris is right, and all Iband epochs
for SN99Q are wrong by 0.4 mag.
Since fitting the tmax as a free parameter or not, changes our estimate of
the color excess for this SN, we need to understand better what we trust
best. How reliable is the extinction estimate given by SNminuit? What
intrinsic B-V color is assumed by the code for calculating the extinction?
Moreover, 7 days difference between our fit and Tonry's on tmax seem
unreasonably too large a discrepancy. If this is due to what
lightcurve template we are using for fitting the data, I am very surprised
we get the same cosmology results as the other team does.
Another point you make is that recent results of sn99ff show this SN is
extincted. What results are you referring to?
Cheers,
Serena
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