From: clidman@eso.org
Date: Wed Apr 10 2002 - 01:01:41 PDT
Dear Greg,
My understanding would be that we would target the SNe with the chance that
we might see some host galaxy lines, which would then help us to decide whether or
not the host was in the interesting redshift range. I still plan to put the offset star and the SNe
in the slit at the same time, so we will see a host in perhaps 50% of the cases. The plan for
the first night is to spend at most one hour per SNe. If we see a host line with z < 0.85, we will not
observe it the next night. If we do not see anything from the host, we will continue to observe
it the second night until we have spent three hours.
Cheers, Chris.
Greg Aldering wrote:
> 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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