In article ,
(sean) writes:
[Referring to Knop et al., 2003 ApJ 598, 102 or the preprint thereof]
There are 13 readings
averaged out to 4.8 by my calculations so I`m not sure whether the
single peak measurement point at 1.2 on the graph represents the
`averaged` reading of 4.8 or the one peak reading of 5.89.

It's pretty obvious if you compare the table and the graph and note
the open/filled circles, as the figure caption explains. The open
circle just below 1.2 represents the 13 "BTC" measurements, the
filled circles at 1.0 are the two HST measurements (3.83, 3.89 in
Table 11), and the open circle at 0.8 with the big error bar
represents the WIYN measurements. Thus "1.0" on the figure is
something like 3.9 in the table (probably the 3.89). One magnitude
fainter is 1.56 in the table, very close to 1.54 measured at day
50846.7. (I didn't pick this SN as an example at random!)

this is shown on the graph as 1.2 mag at day 50817

Not "mag"; linear flux density.

and my guess is
1.2 probably represents the averaged lower mag value of 4.8.

Close enough; I get 5.1. Did you weight the measurements when you
took the average?

One problem I have is that the 1.2 `reading` on the graph does not
decay by one mag to 0.4 as you suggest but rather to 0.48 linear
(using the calculation 1.2/2.5=0.48) .

Look at the error bars! The "1.2" is highly uncertain. The two HST
measurements around the same time have much smaller uncertainties.
Those are what establish the peak of the light curve, which
conveniently is put at 1.0 in the graph.

Giving a time in days for
0.48 mag is difficult to do accurately on the graph, but from the
graph 0.48 occurs at about 21-22 days after peak, not 29 days!

Again not "mag," and you are looking for 0.40, not 0.48.

Unfortunately 1997ek is one of only a couple where there is *any*
chance of defining a peak reading that has been observed rather
than inferred by the template.

There's nothing wrong with using the templates. In fact that's the
"right" way to do things because the time of maximum, where the light
curve is flat, is hard to determine. Fortunately, the authors have
done the work for you. If you don't like the template, look at the
time to decline an additional 0.78 mag (from 1.54 to 0.75 in Table
11), 12.1 days. The corresponding time for 1995E is about 5 days.

There are many more supernovae published than in the Knop et
al. paper. All we are looking for here is a sanity check. Probably
a hundred or more astronomers spend most of their time working on SN
light curves. If there were no time dilation, don't you think one of
them would have noticed by now?

And the templates are not an accurate enough guide as one
only has to see how in SN1997eq and ek the actual peak
measurements are well above the inferred template peak of 1

Only if you ignore the error bars.

Incidentally,are you sure that 1995E is 0.01 redshift? It seems
to be in the mid range of `heliocentric redshifts` (on table 3
page 51 Reiss) at 3.54 in a range between 3.1 - 4.5 (or 0.01 - 0.1)
but unfortunately I dont know how to convert `heliocentric` to z.

The table is labelled "log cz." Take 10^(cz) -- sometimes called
"antilog" -- then divide by c=3E5. You have to know the units meant
are km/s. You can check by looking up the galaxy velocity (NGC 2441,
3470 km/s). So yes, I'm sure, z=0.012. I didn't pick this SN at
random, either.

In every post, you have made elementary mistakes. I am not sure what
to suggest, but you need to learn how to interpret data if you want
to pursue this project (or indeed any other in astronomy).

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
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