From: Andy Howell (howell@astro.utoronto.ca)
Date: Wed Apr 28 2004 - 15:25:01 PDT
Chris,
I re-ran C02-028 as you suggested, with no color mangling allowed.
You do have to subtract about half Sa galaxy to get the color to
match though. See attached comparison to a Ia at +5d.
I am still not convinced it is a Ia. It is not out of the question
though.
-Andy
On 26 Apr 2004, Chris Lidman wrote:
> Hi Andy,
> I've been having a closer look at C02-028. This one is currently
> classified as "?".
>
> Could I ask you to try this one again, but with the extinction turned
> off. It will be difficult because it is dominated by the host. The
> reason why this could be a SN~Ia is that:
>
> i) The H and K absorption from the galaxy do not form a clean
> 4000 Angstrom break. There might be some light from the blue
> emission wing of the CaII feature of the SN.
>
> ii) A bump at 6600 Angstroms.
>
> iii) A reasonable looking light curve. See the attached plot. (You will
> see from the tiles why this was a difficult one to do spectrally.)
>
> The spectrum was taken on May 18th, about 4 days past Maximum light.
>
> Perhaps we can get a better match with these constraints.
>
> Cheers, Chris.
>
> On Mon, 2004-03-08 at 17:53, Andy Howell wrote:
> > Chris,
> >
> > I have mande several improvements to my program recently, most notably
> > better outlier rejection and better handling of error spectra, so it
> > certainly is worth rerunning objects for which we have questions. In these
> > plots, blue is the rebinned spectrum after host galaxy subtraction
> > (usually 5 A binning for these plots), black is the low-z template, and
> > green is the original data.
> >
> > I have attached 5 postscript plots of the best fits to the 4 SNe you sent.
> > > S01-004 - currently classified as ?
> >
> > Rerun with no host. The fit here shows a comparison to SN 1993J at +17d
> > at z=0.41 (z is not known from the host). The fit isn't that bad. Do we
> > know the date our spectrum was taken with respect to maximum light? I'm
> > sure +17d is too late, but these IIb's have different features come in at
> > different times depending on the relative thicknesses of the H and He
> > envelopes. I wouldn't say that it is either a II or Ib for certain, but I
> > think it is unlikely that it is a Ia. How about (IIb?) for the
> > classification?
> >
> > > S01-028 - currently classified as ?
> > > Significant host contamination. The percentage increase is only 27%.
> > > Previously, we had this one as Ia?
> >
> > As you say, the host contamination is pretty bad. Here I show a
> > comparison to SN 1999ee (Ia) at -8d after subtraction of an SB6 host
> > galaxy. I find it very unconvincing. CaII should be obvious but is
> > not. Still "?" as far as I'm concerned.
> >
> > > C02-028 - currently classified as ?
> > > Another one with significant host contamination. The percentage increase
> > > is only 13%.
> >
> > C02-028_spec.1.ps shows the comparison to SN 1999aa at -1d.
> > The blue side looks ok, and it is possible that the feature at 9000A is Si
> > 6150. The problem with this interpretation is that the SII "W" at rest
> > 5400A should be there, but it isn't! Neither is the "emission" (really
> > lack of absorption) just blueward of it at rest 5100A.
> >
> > C02-028_spec.18.ps shows a comparison to SN 1987K (II) at +7d after some
> > serious host galaxy subtraction and mangling of the color. I don't
> > believe it either, but it shows the difficulty in narrowing down the type.
> >
> > > SuF02-002 - currently classified as ?
> > > This one has some host contamination. Previously we had Ia?
> >
> > Ugh. This one is disgusting. About the only thing I can say is that it
> > is not inconsistent with a Ia. But on the other hand, there isn't
> > anything to make me believe it is a Ia either!
> >
> > -Andy
>
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