(sean) wrote in message ...
I`m not sure what you mean "by consistent with 1" ?

My comment was "not consistent with 1," i.e., the data are NOT
consistent with absence of time dilation. I probably confused you by
mistyping one of the numbers. The one-mag decay time of 1998ek in I
looks like about 29 days from the graph in Fig. 1 of astro-ph/0309368;
I typed 39 but used the correct 29 in my next paragraph. This
compares to 17 days for 1995E in B band. There is no way 17 and 29
are equal, no matter how much you stretch the error bars.

Is that when you
compare the ratio between the days it takes a low redshift SN to
decay by one mag as compared to how many days a high redshift SN
decays the same mag? So if its `1` then thats a 1/1 ratio ie they both
decay at the same rate ? .

Yes exactly. If there were no time dilation, the decay times would be
the same, i.e. have a ratio of 1.

I checked 1995E (Reiss pg 23 of his paper..... arXiv:astro-ph/9810291
vl 19 Oct 1998).. and I seem to get completely different results from
reading the data that you have.
I agree with you that it takes only about 17 days to decay by one
mag in the B band lightcurve of 1995E.

OK. We agree here.

However with the I band in 1997ek (Knop) I found that the 0.4 reading
is clearly stated in the tables as being 22 days and not 29 days, as
you claim, after the highest (peak luminosity ) reading for SN1997ek .
This is the HST reading of 1.54 on julien day 50846 which on the graph
is represented in linear as 0.4 mag.

I agree with your date (actually 50846.7) at which the decay is one
magnitude. I'm looking at Table 11.

(It is clearly the brightest mag
reading in I band for that SN despite being placed at about 8 days
past peak on the graph.I assume thats for convenience to fit a
theoretical template. Nonetheless it is the brightest mag for I band
and thus for me the decay is 22 days from 1 to 0.4 )

I have no idea what you mean by this. The brightest single
measurement is at day 50817.65, a value of 5.89 +/- 1.23. There are a
bunch of other measurements near the same time. I haven't bothered to
pull out a calculator, but by eye, they average to something a bit
above 4, and this is the time of maximum. The time difference is
50846.7-50817.65=29 days, just what I got by reading off the graph.
For "by eye" work, the graph is better because some of the points have
already been averaged, and the graph includes the standard decay
curve.

So the ratio I get is 22 days for high redshift as compared to 17 days
for low redshift which is much closer to 1 than you have calculated.

Let's see... 22 days from 50846.7 (when we agree the decay has reached
one magnitude)... you are claiming that maximum was at 50824.7.
There's an HST measurement of 3.83 at that date, but it is clearly
well after maximum. Look again at all those measurements near
50846.7.

A more extreme example is 1998as, which was not observed in I until
well past maximum. If you took the first measurement to be the time
of maximum, you would get a wrong answer, as you can see from the R
measurements.

And to explain this small difference without invoking any time
dilation at all , I do the following calculation..The high redshift I
band (Knop ) which you calculate as being an emission wavelength of
438nm is compared to the Reiss B band , but , remembering that Reiss B
band is still a 0.1 redshift,

That is 0.01 for 1995E, as stated in the earlier post.

this means that the low redshift 1995E
B band actually was an emission wavelength of 390nm. Thats a 50nm
difference between the two that are being compared incorrectly as like
for like. And if one then notes that the time it takes a low redshift
530nm V band from Reiss 30 days

How are you getting 30 days? Looks like about 18 days to me;
certainly not more than 20 (again based on 1995E). The V maximum is
two or three days later than the B maximum, but V is a magnitude below
its peak no later than 21 days after the B maximum.

If you want to do all this "right," you need to do a large sample and
take account of filter bandwidths, exact redshifts (K-correction), and
all the uncertainties. However time dilation is obvious on a casual
glance.