From: Chris Lidman (clidman@eso.org)
Date: Sat Nov 13 2004 - 07:23:31 PST
Dear Serena,
We reviewed your I-band paper paper during the last SCP
executive meeting, and there are a couple of paragraphs we would
like you to reword. Below, we provide some suggestions on how these
paragraphs can be reworded.
Once these changes are made, please send a copy to Tony. He will
distribute it to the collaboration so that they have the chance to
read the paper one last time before it is submitted. We hope that you
will be able to submit the paper in 10 days from now.
Here are the changes we request.
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1) Delete the second last paragraph in section 5 and merge the 4th and
6th paragraphs into one. We do not believe that the ground-based IR
photometry in this paper is less accurate than ground-based optical
photometry in general.
2) Rewrite section 4.3. Here is a suggestion.
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 adopted Milky Way reddening 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 Telescope
(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
difference of up to 0.15 magnitudes between our k-corrections and
those published in Riess et al. (2000). The rest frame I-band
magnitudes, using the published infrared photometry with our
k-corrections, are reported in Table 7. We note; however, that a
re-analysis of the publicly available SofI data suggests that the
published J-band magnitude may be too faint.
We have also re-analysed the publicly available restframe B- and
V-band HST data on SN 1999Q, 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
$t_{\rm max}=$ MJD 51194.65 (Tonry, private communication). If the
date of maximum is left as a free parameter in the fit, we find that
it occurs 8 days earlier and we measure a larger value for the
stretch, $s=1.18 \pm 0.04$.
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 published restframe 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 potentially makes SN 1999Q an interesting object.
Although we fit a lightcurve to the rest frame I-band data of SN 1999Q
and we include it in all the plots that follow, we do not include it
in our analyses. We will defer this to the time when the discrepancy
in the J-band photometry is understood.
-----------
There is one point that remains a little unclear. What is the
reasoning for adopting the Tonry Date of Maximum? This point should
not delay the release of the paper to the entire collaboration, but we
should discuss it before the paper is submitted.
You should double check the epochs listed in Table 7. Using the Tonry's
date of maximum, I get +6.5 rest frame days for the first I band point.
Regards,
Chris (On behalf of the SCP exec.)
-- European Southern Observatory Alonso de Córdova 3107, Vitacura Casilla 19001, Santiago 19 CHILEPh. +56 2 463 3106 FAX +56 2 463 3001
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