From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Tue Apr 09 2002 - 12:07:02 PDT
Dear Ariel & Chris,
Maybe I'm confused, but it seems to me that the only reason to observe
a host galaxy rather than the SN itself is a) if you think the host
will have strong emission lines or b) the host has a higher apparent
(seeing convolved) central surface brightness than the SN. Otherwise
the SN itself is an easier target (both in terms of SN/pixel, and if it
is a Ia, in terms of ability to secure a redshift).
I completely understand the idea of using host-galaxy brightnesses to
help select SNe that might be in the desired redshift range since we
have used the approach at Keck for the last several years now. However,
once that selection has been done, it seems the SN itself should be
targeted. At high-z it can be hard to separate the host and the SN
anyway, so the distinction may be mute.
> Ariel Goobar wrote:
>
>I mentioned this possibility to Saul last night. The thing to remember is
>that if you assume that the rate of Ia's is proportional to the rest-frame
>B-band galaxy magnitude, then you expect about 50% of the SN host
>galaxies with 22<I<23 to be at z>0.8 (see Dahlen & Goobar, PASP, also
>in astro-ph/02 + something.
> Ariel Goobar wrote:
>
> > Dear Chris,
> > w.r.t the issue of trying out how FORS2 works there is
> > another possibility worth considering. Assuming we get Subaru
> > candidates in the next hours we may want to start with a shorter
> > exposure (<1 hour) of a host galaxy for a case where there is a
> > good candidate on top of a visible galaxy. If the galaxy redshift
> > is in the interesting range we could go for the SN the next night.
> > By then we would also know the performance of the instrument.
> > Cheers,
> > Ariel
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