From: Gabriele Garavini (garavini@in2p3.fr)
Date: Mon Feb 21 2005 - 09:11:29 PST
Dear All,
please find at : http://supernovae.in2p3.fr/~garavini/papers/
the new version of the Evolution paper.
I've implemented the changes Chris requested and changed the section about
the EW hopefully clarifying the issued brought up by Rob and Eric, and
accordingly to my last e-mail.
To sum up the latest developments on the EW measurements technique and
possible systematic effects, Eric and myself have been exchanging few
measurements on the same data set. The conclusion was that even if Eric
did not provide any uncertainty estimate on his measurements the value he
obtained, this time following Gaston technique to measure the EW, did not
appear to be that off, usually within my estimated uncertainties. The ends
point he choose were a bit different from what Gaston had chosen ( Looking
at the spectra I would have chosen endpoints closer to those Gaston
choose.).
This suggested me that there might be a systematic related to the
experience of the observer. Is like people being able to classifying a SN
from a noisy thing in which other would see nothing.
So I thought of making a small Montecarlo to estimate an **upper limit**
to such possible systematic effects and to report this study in the paper.
The table 4 now reports two uncertainties for each EW measurements. The
first one including statistical and host galaxy contamination
uncertainties, the second one, including also this uncertainties added in
quadrature. This value is an **upper limit** in the sense that the sigmas
used for the Montecarlo where chosen in a conservative way to account also
for large miss-identification of the maxima. I did not plot or took into
account this uncertainties in the statistical test because I regard these
as upper limits. Using them to draw conclusions would be inappropriate. I
want them to be there to turn the attention of the reader on a possible
systematic that is difficult to quantify properly.
The measurements technique it has been spell out in a itemized section
3.2.1. I think is clear now.
Section 3.2 now includes all the discussion I just summarized.
Please let me know your comments to this new draft.
Thank you All
Cheers
Gabriele
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