From: Lifan Wang (lifan@panisse.lbl.gov)
Date: Sun Mar 28 2004 - 16:37:54 PST
Hi, Chris,
As I said in my previous email, I scaled the OBSERVED spectra
by a CONSTANT to show how those compare with your template. I do not
believe the observations can be systematically wrong (redder than) the
template.
In calculating the K-correction, all the spectra are
redshifted and scaled so that they have EXACTLY the OBSERVED color. My
calculations are based on colors only, and dates are not really a
primary parameter in the calculation. I ONLY used 94D to convert my
K-corrections to dates to make those plots.
I do not believe R-I can be anywhere close to -0.4 at optical
maximum of a normal SN Ia. My light curve fits show most of the SNe
with z
< 0.005 show -0.24 at B-max. R-I = -0.4 is beyond reasonable physics.
I am overwhelmed by some other issues, but am indeed preparing
some better figures to explain the difference.
Cheers,
Lifan
On Sun, 28 Mar 2004, Chris Lidman wrote:
> Dear All,
> I've had a closer look at the comparison that Lifan sent us a few
> days ago. For reference, I
> attach the plots that he sent us last week.
>
> If one looks carefully at the R- and I-band regions, then the
> derived R-I colours must be
> grossly different and it seems to me that it is the colour and less so
> the features that is
> the driving reason behind the difference in the k-corrections at
> maximum light.
>
The template is just one "SN" in my calculation, and I have found
that it is unlikely to be an "SN" that resembles the other ones.
> Lifan, how does your R-I colour compare with those published in
> Nobili et al. 2003, AA,
> 404, 910? At max, Serena finds R-I ~ -0.4 (this is from fig. 7 in
> Serena's 03 paper). The
> spectra you present are considerably redder.
>
> The opposite is true for V-R. The spectra you sent us are
> considerably bluer than Serena's
> template. Serena's V-R colour is ~ 0.0 (again, this is from fig 7. in
> Serena's paper).
>
My V-R color is around 0.0.
> Cheers, Chris.
>
>
>
-- Lifan Wang (510) 495 2733 (o) (510) 704 0119 (h)
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