From: Chris Lidman (clidman@eso.org)
Date: Wed Apr 28 2004 - 15:52:58 PDT
Hi Andy,
Thanks for re-doing the fit. Do you think it is reasonable if we
classify C02-028 as Ia?
Cheers, Chris.
On Wed, 2004-04-28 at 18:25, Andy Howell wrote:
> 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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