From: Chris Lidman (clidman@eso.org)
Date: Sun Dec 19 2004 - 12:53:26 PST
Dear All,
I think that Rob and Eric have raised as issue that needs to be
discussed on Tuesday.
I attach the most recent version of Gaston's paper (version Jan. 22
2004). A description of the method that was used to determine the
bounds over which features are measured is given in section 3.2.
Gaston worked with spectra that had good S/N ratios and the
description given in section 3.2 might be sufficient for such spectra.
The spectra with the lowest S/N ratio in Gaston's paper has a S/N
ratio of 5. Gaston did not find any systematic effects when the
S/N ratio of the best spectra were reduced to such a level. This is
reasonable.
However, such a S/N ratio is probably higher than S/N ratios of
most of the high-z SNe in Gabriele's paper. Hence, it seems reasonable
to ask Gabriele or Gaston to check for systematic errors when the
S/N ratio is reduced to the levels that are typical for high z SNe.
For such low S/N spectra, it would seem that some sort of rebinning is
necessary before features can be identified and measured. Gaston, were
the high-z spectra rebinned before the EWs were measured?
Cheers, Chris.
PS The last message in the e-mail archive is dated January 26th, 2004.
This e-mail contained the minutes of a meeting we had on Gaston's paper
and it contained suggestions on how the collaboration thought the paper
could be improved. Gaston, let us know if you are still out there. I
might send a search party to La Serena to find you :)
On Fri, 2004-12-17 at 17:10, Robert A. Knop Jr. wrote:
> On Fri, Dec 17, 2004 at 11:59:45AM -0800, Tony Spadafora wrote:
> > I've put more time for the evolution paper because this paper has been
> > before the collaboration since July. The discussion here should be to
> > confirm that all issues have been resolved (e.g. the systematics of the
> > equivalent width determination) and, if so, that a submission-candidate
> > version should be finalized and submitted soon.
>
> For the record: I'm not convinced at all that the systematics in the EqW
> determination are resolved. So far, all that's happened is that the
> issue has been raised. More basically, the method for determining
> them from noisy spectra needs to be documented in the paper; all that
> Eric and I have heard so far is that "Gaston did it" is the method,
> which obviously isn't something one writes in a published paper.
>
> Gaston probably really needs to be at this meeting since he is the one
> who knows how the measurements were made.
>
> There's also the issue that this builds on the nearby EqW stuff that
> Gaston has done. If *that* paper isn't published first, then that stuff
> will need to get incorporated into this paper for this paper to make
> sense.
>
> Please include Eric on mailings for this, since obvously he is involved
> with this. Also please re-send the schedule so he gets it.
>
> -Rob
-- European Southern Observatory Alonso de Córdova 3107, Vitacura Casilla 19001, Santiago 19 CHILEPh. +56 2 463 3106 FAX +56 2 463 3001
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