From: Rachel G. (gibbo@panisse.lbl.gov)
Date: Thu Mar 11 2004 - 19:44:21 PST
My attachment was too big to post to hstsearch, so
I'll refer anyone interested to the search pages because
I'm not sure where else to post them at this point :
http://panisse.lbl.gov/collab/observing/schedule2003/hstc12/hstsearch/acs_grism_spectra.pdf
---------- Forwarded message ----------
Date: Thu, 11 Mar 2004 18:55:59 -0800 (PST)
From: Rachel G. <gibbo@jimbean.lbl.gov>
Reply-To: Rachel G. <ragibbons@lbl.gov>
To: Chris Lidman <clidman@eso.org>, Andy Howell <howell@astro.utoronto.ca>
Cc: hstsearch@lbl.gov, Mamoru Doi <doi@ioa.s.u-tokyo.ac.jp>
Subject: Re: SuF02-012
Hi Chris and Andy,
I will send you the ACS spectra for both SuF02-012 and
SuF02-060 tomorrow. I realize I need to recalculate the
error spectra since my last reduction.
In the meantime, I've attached plots comparing the ACS
spectra to the various ground-based spectra :
SuF02-12 :
figs 1-2 = Subaru
figs 3-4 = VLT
figs 5-6 = Subaru+VLT
SuF02-060 :
figs 7-8 = Gemini
figs 9-10 = VLT
Also included are Lifan's best matches (figures 11 &
12).
N.b., Lifan wants to do a more careful galaxy
subtraction for both of these candidates and for SuF02-060
use a finer redshift grid when fitting - he used bins of
0.01. I'll let him elaborate.
We think the redshift determination for SuF02-012 is
quite robust and = 1.28. The redshift of SuF02-060 is
1.04-1.05. This latter spectrum clearly contains host galaxy
light which is relatively bright, contributing more than 50%
of the flux in Lifan's fits.
Interesting also for this candidate is that there could
be contamination in the ground-based spectra from a second
galaxy which is pulling the fits towards a slightly higher
redshift (see figs. 13-16) -- whereas the ACS spectrum
doesn't suffer from this problem (fig. 17). Furthermore (to
make nice figures) I had to apply a linear renormalization
to the ground-based spectra in order to better match them to
the ACS spectrum.
Regarding the ESI spectrum, I believe Lifan has those
data?
Rachel
On 11 Mar 2004, Chris Lidman wrote:
> Hi Rachel, Vallery,
> Could either of you provide Andy with the ACS spectrum of SuF02-012
> together with an error spectrum. It might be interesting to combine
> the ACS/VLT/Subaru spectra into a single spectrum.
>
> Does anybody know who reduced the ESI data on SuF02-012?
>
> Cheers, Chris.
>
> On Wed, 2004-03-10 at 13:37, Chris Lidman wrote:
> > Hi Andy,
> > Thanks for the plot.
> >
> > The Subaru data is available from http://www.sc.eso.org/~clidman/#L2742
> >
> > I weighted the VLT and Subaru spectra (using the error
> > spectra) before combining them. In principle, one could add the ESI and
> > ACS data as well if the the error spectra for these supernova are
> > available. The ACS data appear to be in good agreement with
> > the VLT and Subaru data. I know very little about the ESI
> > data. You might have to ask Rachel, Vallery and Greg about the
> > ACS/ESI data.
> >
> > Cheers, Chris
> >
> >
> >
> >
> >
> >
> > On Wed, 2004-03-10 at 11:52, Andy Howell wrote:
> > > You are right -- I attached the wrong plot! Here is the correct one.
> > > The ACS plot looks pretty good.
> > >
> > > Your first mail said that it was a combined Subaru and VLT plot. I didn't
> > > even know there was Subaru data on this one. According to the
> > > spectroscopy web page we have ESI data as well.
> > >
> > > Any chance you could make a combined ESI, FORS1, Subaru, ACS spectrum,
> > > maybe combining weighted by the errors? I think Peter has a program to
> > > do such a thing. If not, if all of these have error spectra, I could
> > > write something to do the rebinning and combination -- I have most of the
> > > framework already for my program.
> > >
> > > -Andy
> > >
> > > On 10 Mar 2004, Chris Lidman wrote:
> > >
> > > > Hi Andy,
> > > > Thanks for the plots. The first one seems to be a plot
> > > > of SuF02-002. Perhaps, you attached the wrong PostScript file.
> > > >
> > > > I've cc'ed this e-mail to Rachel and Vallery as both have been
> > > > involved in the reduction of the ACS data on this elusive candidate.
> > > >
> > > > I attach a comparison plot of the VLT/ACS data that was sent to me
> > > > by Vallery. The ACS data also show a dip at ~9200 Angstroms.
> > > > If this is Si4000, then this might point to a type Ia at z=1.26.
> > > >
> > > > Cheers, Chris.
> > > >
> > > > On Tue, 2004-03-09 at 21:46, Andy Howell wrote:
> > > > > Chris,
> > > > > This spectrum is better! I get z ~ 1.26, or z ~ 1.02 (see attached). I
> > > > > prefer z=1.02.
> > > > >
> > > > > -Andy
> > > > >
> > > > > On 8 Mar 2004, Chris Lidman wrote:
> > > > >
> > > > > > Hi Andy,
> > > > > > I've combined the Subaru and VLT spectra of SuF02-012 into a
> > > > > > single spectrum. The spectrum and the associated error spectrum are
> > > > > > available at
> > > > > >
> > > > > > http://www.sc.eso.org/~clidman/
> > > > > >
> > > > > > This candidate has been placed at various redshifts, anywhere from
> > > > > > z=0.9 to z=1.6. The wiggles in the combined spectrum are more
> > > > > > pronounced, but finding a redshift will be hard.
> > > > > >
> > > > > > Cheers, Chris.
> > > > > >
> > > >
> > >
> >
> >
>
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