From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Wed Oct 20 2004 - 16:56:41 PDT
Other issues aside, let me comment on the Tonry optical data for 99Q. I
sat beside John in his office as we examined the HZSST's fit to 99Q. He
provided me with the date of max from his published fit. We looked over
the lightcurve file used in the fit. Although I did not feel I could write
down each value, I noticed that the data list started with the discovery
point and continued with the HST points. The discovery point is exactly as
listed in the IAUC - and based on Tonry's data of max I assume the
discovery point is the pre-max point that is referred to. (In our fit the
discovery point is not pre-max).
Somewhere in the conversation Tony mentioned that for all he knew Adam
night have addition points, but Tonry didn't know this and didn't use any
such data. Therefore, I believe that Vitaliy's fits 2R, 2P, 2S are
accurate, complete, and self-consistent with respect to the data used in
the Tonry paper. As the fit is completely controlled by the lightcurve
template and the K-corrects well after max, it may not be surprising that
our dates of max could differ so much. Of course if Tonry was showing me
the wrong file, or forgot some other important details, then all bets are
off. Likewise, if Adam used different points in his analysis, we would not
know that.
Cheers,
Greg
On 20 Oct 2004, Chris Lidman wrote:
> Hi Serena,
> Many thanks for the very quick reply. Here is some follow-up.
>
> > > Section 4.3
> > > -----------
> > >
> > > 2nd paragraph
> > >
> > >
> > > I think you should delete the last sentence concerning the IR
> > > photometry in this paragraph. Although I have re-reduced the data,
> > > I'd like someone to check my estimate of the magnidude independently.
> > >
> >
> > Is someone checking it? I think it is important to say that we have
> > doubts about their IR data, otherwise I don't see the whole point of
> > excluding this SN from the analysis. The doubts on the optical lightcurves
> > are not enough since there should be more ground based data that we don't
> > have (at least according to Riess' paper).
> >
>
> I'll ask Ramon to check my IR photometry estimate.
>
>
> >
> > > 3rd paragraph
> > >
> > > According to http://panisse.lbl.gov/collab/archive/iband/0056.html
> > > the time of B-max in case 3 is 51190.4 +/- 1.5 days, which is only
> > > 4 observer frame days before the Tonry value and not 8 days which is
> > > based on the HST data alone. I think that you should change the 8 to 4.
> > >
> >
> > The latest fit by Vitaliy is:
> >
> > http://panisse.lbl.gov/collab/archive/iband/0150.html
> >
> >
>
> Thanks for the plot.
>
> This plot makes me nervous as there is no data before
> maximum light. Hence, I do not think that the estimated
> errors in the stretch and the date of maximum light are
> particularly reliable.
>
> Hence, I think that you were correct in using the Tonry date as they
> have presumably done the fit to data that includes points that
> were taken before maximum light. At the same time, I do not think we
> should mention that we find a different date for the maximum as we
> are probably using an inferior data set.
>
> I would suggest that you replace section 4.3 with something like the
> following
>
>
> SN 1999Q was discovered by the HZSST using the CTIO 4m Blanco
> Telescope and was spectrally confirmed to be a Type Ia SN at $z=0.46$
> (Garnavich et al. 1999). The reddening due to our galaxy is E(B-V) =
> 0.021 magnitudes (Schledel et al. 1998).
>
> SN 1999Q was observed in the J band over five epochs, the first
> with SofI on the ESO NTT and the following four with NIRC at Keck
> Telscope (Riess et al. 2000). We recomputed the k-corrections using
> our new spectral template (as we did for SNe 2000fr and 1999ff) and
> we find a disagreement of up to 0.15 magnitudes between our
> k-corrections
> and those published in Riess et al. (2000). The rest frame I-band
> magnitudes, obtained with our k-corrections, are reported in Table 7.
>
> The restframe B- and V-band data on SN 1999Q have not yet been fully
> published;
> however, the HST data is publicly available, and together with the
> discovery point reported in the IAU circular (Garnavich et al. 1999),
> we have fitted the lightcurve and computed the B-band stretch, which
> we find to be $s=1.10 +/ 0.03$. Since these data do not
> adequately cover the rising part of the lightcurve, we force the date
> of maximum to occur at 51194.65 (Tonry, private communication) and we
> note that there may be a significant systematic error in the fitted
> stretch.
>
> The restframe B-V colour is considerably redder than the average SN Ia
> with $s=1.1$ (see figure 13), which might mean that SN 1999Q is
> significantly reddened or that the stretch has been overestimated. In
> contrast, the B-I colour is quite normal for a SN Ia with $s=1.1$ (see
> figure 13). As we will show in the sections that follow, SN 1999Q is
> also unusually faint in the rest frame I-band. This makes SN 1999Q
> an interesting object.
>
> For these reasons, we fit a lightcurve to the rest frame I-band data
> of SN 1999Q and we include it in all the plots that follow; however, we
> do
> not include it in our analyses. We will defer this to the time when
> all the data, including the spectrum and the ground based optical
> photometry, have been published.
>
>
> > > 2nd paragraph
> > >
> > > I have a question about the B-I colours of 99Q. Do we use the B-band
> > > magnitudes of Riess et al., or do we redetermine them from the HST data
> > > that was retrieved from the archive using our own light curve fitting
> > > software and our own k-corrections?
> > >
> > >
> >
> > We use the B-band magnitudes of Riess et al for consistency reasons, since
> > we are also using the time of Bmax by them. As I said, I don't like using
> > our optical lightcurve fit, since there could be more data.
> >
>
> How do our B-magnitudes compare to theirs?
> >
> > > Section 7
> > > ---------
> > >
> > > 2nd paragraph
> > >
> > > "colors" -> "the colours" (note the English spelling)
> >
> > I believe I used the American spelling throughout the paper
> > (e.g. gray instead of grey). But maybe I have not been consistent. If so,
> > please let me know.
> >
> >
>
> I think A&A requires British spelling (and grammar) :)
>
> Chris.
>
> >
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