From: Lifan Wang (lifan@paloma.lbl.gov)
Date: Wed May 15 2002 - 20:07:02 PDT
Andy,
I guess the the difference is that we are applying different extinction
corrections to 94I which is quite uncertain and is even somewhat arbitrary -
with published values from Av=3.1 to 1.0. Have you applied extinction at all ?
Now that Rob has provided a phase estimate it seems more likely that this
can actually be a Ia at z = 0.34. In my X^2 plot, pre-max fits favors z = 0.56,
post-max favors 0.3+.
Lifan
> From DAHowell@lbl.gov Wed May 15 15:35:29 2002
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> To: Lifan Wang <lifan@panisse.lbl.gov>
> CC: deepnews@lbl.gov
> Subject: Re: S02-064
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> Lifan Wang wrote:
>
> > I made a fit with the new data and still think 0.56 to be the
> >best redshift.
> >
> >A Ic at 0.33 11 days past max is highly unlikely as Ic at
> >that phase are too red to fit the observed.
> >
> Lifan,
> I am not sure what you are talking about. The color is fine. If you
> overplot
> the dereddened spectrum of 94I at +11d on S02-064 they lie right on top
> of each other. See:
> http://panisse.lbl.gov/collab/data/spec/homesp/2002/S02-064/S02-064.94I.jpg
> or go here for the big picture:
> http://panisse.lbl.gov/collab/data/spec/homesp/2002/S02-064/S02-064.html
> Here I didn't subtract a host galaxy or monkey with the colors in any way.
>
> If we knew that the host was an elliptical, then we could rule out the
> Ic hypothesis, but
> Peter and I took a look at the host galaxy and we can't determine the
> type from our data.
>
> Also, we did a back of the envelope calcuation, and S02-064 is too
> bright in I to be a clone of 94I itself at +11d, but its magnitude is
> consistent with another Ic, 83V at +11d which has an almost identical
> spectrum at that epoch. Note that I am not saying that S02-064 was
> observed at exactly 11d past max -- we don't have great Ic time
> coverage, so we can't determine the date very precisely just from the
> spectrum.
>
> Actually, I am not convinced that this is a Ic at all. I agree that it
> could also be a Ia.
> The point of my original email on this subject was that we shouldn't
> jump to
> conclusions that it is a pre-max Ia at z~0.55. I thought it was
> post-max and could go either
> way as far as the Ia/Ic identification. I haven't seen anything to
> change my mind on this
> point. But maybe your new fits will convince me. Please send them and
> I will put them on the web page.
>
> -Andy
>
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