From: Serena Nobili (serena@lpnhep.in2p3.fr)
Date: Fri Dec 17 2004 - 06:30:30 PST
Dear Vitaliy, (and Alex)
thanks for the answer. I think I understand your plots better now.
I have a couple of questions:
1. which is the second outlier SN you exclude from Jha's plot?
2. I believe now, that the first point is 1999Y, because that should have
the right stretch factor. I could try to implement the 6 other SNe used by
Jha in my analysis if someone has the data. I have seen that Alex Conley
uses 2001V in the CMAGIC paper.
**Alex, do you have the data for these 6 SNe in the snminuit format?
For the linear versus exponential stretch-color relation, I agree they
both work well in the U-B vs s(U) plot (especially given the scatter of
the data), once the first point (s ~0.6) is excluded. It is too bad that
we rely on 1 point only to define the relation function. In this moment I
do not see any reasons why the relation should be the same in all colours,
so the behavior of B-V vs stretch does not help to define the one of U-B.
Am I missing something important?
Cheers
Serena
PS. I am still not able to use the Twiki...could you put
this email in the web, in case you think it is useful, while we are
fixing my *relationship* with the Twiki...Thanks.
On Thu, 16 Dec 2004, Vitaliy Fadeyev wrote:
>
> Dear Serena,
>
> thanks for your reply and considerations.
>
> Regarding the TWiki registration, it would be best to concact
> our administrator with a description of the problem. His address is
> Vladimir Eberman <eberman@mh1.lbl.gov>.
>
> For now, I just posted your email to the page
> http://supernova.lbl.gov:8080/twiki/bin/view/Albinoni/EmailFromSerena
> Hope this is ok.
>
> In response to your questions I posted some text and plots to the
> following link
> http://supernova.lbl.gov:8080/twiki/bin/view/Albinoni/JhaSneTruncated
>
> Cheers,
> vitaliy
>
>
> Serena Nobili wrote:
>
> >Dear Vitaliy,
> >
> >as you know I am also working on my own on this issue and I can probably
> >help in messing up even more this complicated topic. I want to stress,
> >however, once again I am using the *real* data to compute the colours and
> >not the results of a lightcurve fit (the same as in Nobili et al 2003), as
> >I believe is the case of all the plots you put in the wiki. Moreover, I
> >am fitting a linear relation of colours with the B-band stretch. My
> >finding, however, is similar to yours:
> >
> > (U-B)_tBmax = -0.47 for s(B)=1
> >
> >The attached plot shows the result of my fit in a time bin of -1<t<1 days.
> >The fit is actually done on the whole time and stretch together,
> >e.g. without binning the data. The plot has been made only for comparison
> >with yours. Also, as I said above, the points plotted are the real data,
> >only for SN which were observed both in U and B at the same epoch (the two
> >points at the same stretch value are the same SN observed twice in this
> >time interval).
> >
> >I have some questions and comments about your plots, in particular U-B vs
> >S(U). First, the exponential function you fit on the plot is mainly
> >determined by the point at very low stretch (s ~ 0.6) which I believe is
> >sn1997cn. Is this correct? If you take that point away, a linear relation
> >would work quite well to fit the data. I am personally not including this
> >SN in the analysis, also due to the difference of 0.15 mag , also
> >discussed by Jha in the thesis, with the U-band published by Turatto et
> >al. for the same SN.
> >
> >On the same line, there is another object, SN1997bp, whose U-band was
> >published by Altavilla et al 2004 (same group as Turatto), for which the
> >discrepancy with Jha is ~0.2-0.3 mag. So, it might be dangerous to include
> >this SN in your fit. Other 2 SNe, SN1997br and SN1999aa, also observed in
> >U-band by Altavilla et al. are quite in agreement with Jha's
> >measurements.
> >
> >I hope I helped the discussion.
> >Cheers,
> >
> > Serena
> >
> >PS. I apology for sending the file instead of adding it in the TWiki
> >page. I tried to register, but it does not like my name so I was unable to
> >do so (although I did use SerenaNobili). Can someone help me with that?
> >
> >
> >On Wed, 15 Dec 2004, Vitaliy Fadeyev wrote:
> >
> >
> >
> >>Dear SCPers,
> >>
> >>the following TWiki page describes a color treatment for Albinoni analysis.
> >>Since the topic is relevant for other on-going analyses, and also
> >>because there
> >>is a difference with the color assumed in Knop 03 paper, we call your
> >>attention
> >>to the issue, and solicit feedback.
> >>
> >>Direct link to TWiki page:
> >>http://supernova.lbl.gov:8080/twiki/bin/view/Albinoni/ANoteOnColor
> >>
> >>Instruction on how to access the SCP TWiki are here:
> >>http://supernova.lbl.gov/collab/
> >>
> >>Cheers,
> >>vitaliy
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
> >
>
>
>
>
------------------------------------------------------------------------ http://supernovae.in2p3.fr/~serena/ Tel +33 1 44277329
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