From: Ariel Goobar (ariel@physto.se)
Date: Fri May 03 2002 - 06:04:22 PDT
Hi All,
nice to see that so many of you are thinking of the use of colors
for candidate selection. At some point I should go through this
in more detail. Then I should also include host
galaxy reddening, stretch distribution, intrinsic color, MW reddening
a.s.o. As for now, I just wanted to get you interested in how we can
make a better use of the search data we have at CFHT.
(and I seem to have succeded with the interest part, at least).
So, for Rob's questions:
I do simulate the spread in discovery epochs.
> Ariel-- are you assuming "at max"?
No.
>The slopes of the color curves are
> pretty steep. How does a z=1 at max compare to a z=0.7 five days after
> max?
"z= 1.0+-0.05 day=0 " -> R-I 1.3 +- 0.05
"z= 0.7+-0.05 day=+5" -> R-I 0.6 +- 0.06
That is, for a stretch=1 Nugent/Rob template.
As for the general case, once you select a magnitude threshold and
a time gap, the range of discovery days are rather narrow for
each redshift (especially in the z>1 range for us), that is why I was
finding typical R-I distributions with RMS of just ~0.1
The other use of colors is to identify possible non-Ia's before
going to VLT/Keck.
Let's hope we get any real data soon so we can argue about all this
with some real goal!
Cheers,
Ariel
-- ___________________________________________________________________ Ariel Goobar (ariel@physto.se) FYSIKUM, Stockholm University Stockholm Center for Physics, Astronomy & Biotechnology tel: +46 8 55378659
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