From: clidman@eso.org
Date: Tue Apr 09 2002 - 21:11:58 PDT
Dear Ariel,
This is a good suggestion and it was something that Saul had proposed.
In terms of grisms, we plan to do the following.
If the candidate is brighter that I=23.4 (The median I-band discovery magnitude for
z=0.75), we will use the 300V grism. If it fainter, we will use the 300I grism.
Even though the 200I grism is slightly more efficient and has a slightly larger
wavelength range, we will go for the higher resolution grism.
Cheers, Chris.
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
>
> On Tue, 9 Apr 2002 clidman@eso.org wrote:
>
> > Dear Ariel,
> > At I=24.5, FORS2 should deliver a S/N ratio of approximately 2 per
> > pixel (3.28 Angstroms) or 4 per resolution element (4 pixels with the
> > one arc second slit) in 3 hours with the 300I grism. There is a second grism, 200I,
> > with lower resolution but increased efficiency. The new CCD is meant to have less
> > fringing, so the 200I may be better, but without data, it is difficult to judge.
> >
> > Although our main aim is to observe supernovae with z > 0.85, we may want to
> > consider observing one relatively nearby supernovae (z<0.5) to make sure
> > everything is working fine. We will be one of the first users of FORS2 with the new
> > CCD.
> >
> > Gaston and I will plan our schedule in the following way. I will stay up until
> > the observations have started and Gaston will come early in the morning to
> > do the data reduction and post the results on the web.
> >
> > Contact Information
> > ===============
> >
> > Gaston and I are sharing an office in Santiago. The number is (++56) 2 463 3106.
> >
> > Our results will be posted at the URL http://www.sc.eso.org/~clidman/
> >
> > Cheers, Chris.
> >
> > Ariel Goobar wrote:
> >
> > > Dear Chris & Gaston,
> > > (CC: Saul)
> > >
> > > as you know, we had a short teleconference about the immediate run.
> > > One of the things that were briefly touched upon is what fraction of
> > > the FORS2 time we should spend in April vs May. We argued that we
> > > probably want to bank >10 hs for May, especially for the early
> > > half nights (May 4-6), as then we should have both Subaru and CFHT
> > > candidates and still 5 mights to go before the first Keck night.
> > >
> > > As the first priority for the april run is 1 SN @ z>1 and 2 @ z~0.85
> > > we are really looking at candidates with I>23.5. In fact, it is
> > > only at I>24 where we have the largest probability of having
> > > a z>1 candidate. That, in turns means, that cannot do more
> > > than 3 candidates this week without exceeding our budget (unless
> > > seeing is superb, of ocurse).
> > >
> > > Maybe you could elaborate a bit more on the table that Gaston
> > > started to do here about the minimal exposure lengths needed
> > > for identifying a Ia at z>0.8. I think it will become important
> > > when making the last minute decission on which targets to observe
> > > at Paranal.
> > >
> > > Cheers,
> > > Ariel
> > >
> > > --
> > > ___________________________________________________________________
> > > Ariel Goobar (ariel@physto.se)
> > > FYSIKUM, Stockholm University
> > > Stockholm Center for Physics, Astronomy & Biotechnology
> > > tel: +46 8 55378659
> >
>
> --
> ___________________________________________________________________
> Ariel Goobar (ariel@physto.se)
> FYSIKUM, Stockholm University
> Stockholm Center for Physics, Astronomy & Biotechnology
> tel: +46 8 55378659
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