From: Rachel G. (gibbo@panisse.lbl.gov)
Date: Wed Oct 29 2003 - 09:33:56 PST
Hi Greg,
I'll be able to answer question #1. I have had
a quick look at this, but should do so in more detail before
quoting expected errors. I don't recall there being a
significant difference in stretch or color errors. I think
stretch is being mostly determined by the good z-band
coverage when additional search points can be used.
I'll also be looking more at the grism question.
I don't believe it's feasible to go to z=1.5 in only 10ish
orbits. I also have grism data for the published z=1.3 SN.
I didn't grab the data from the Blakesley paper, but may do
that too at some point.
On Wed, 29 Oct 2003, Greg Aldering wrote:
>
> Hi Rob,
>
> In your plan there is a big jump in the number of orbits in going from
> cases 1 & 2 to cases 3 and 4; I would suggest an intermediate pair of
> cases, with 6 orbits in z (1,1,2,2), with the option of 9 orbits of grism.
> This would handle SNe of intermediate brightness/redshift, or be an easy
> means to adjust the S/N we wish to reach at a given brightness/redshift.
>
> I'd also like to rise the question of whether there should be additional
> cases offering more J and/or H in the place of grism. We can study this in
> detail later, but there could be benefit to having cases #2'and #2'' with
> 0 grism and one more epoch of J & H (say 3 orbits of J and 3 orbits of H)
> or two more epochs of J (3 orbits each). Likewise, cases #4' and #4'',
> with 0 grism and one more epoch of J & H (say 4 orbits of J and 4 orbits
> of H), or two more epochs of J (say 4 orbits each and then 1 more ref
> orbit). One motivation would be that we could implement C-magic if we have
> the additional color points, which would add a little novelity to our
> program wrt Adam's; and we may be able to distinguish the SN type (albeit
> with somewhat less opportunity, I presume, to abort later orbits than the
> grism might afford) using the color curves.
>
> As it should not be hard to add these additional cases once the other
> cases are entered, I would recommend adding these just so we don't have to
> worry about them later (and then perhaps find that they can't be done). In
> particular, as we must require that NICMOS orbits avoid the SAA, we should
> lock-in as many such orbits we might possible want. Such orbits are very
> valuable and so might be hard to get later on without a big ugly fuss.
>
> Two other issues that we can study after the RPS2 is submitted:
>
> 1) Should the z, J, H observations be at the same epoch - which makes the
> color calculation easier - or at slightly staggered epochs - which
> helps fill in the lightcurve and possibly make the fit more robust?
>
> 2) What is the appropriate number of NICMOS references? If we use
> a model (continuous or pixel-by-pixel), then the observations
> which contain the SN provide information and we wouldn't get all of
> the sqrt(2) hit that pixel-by-pixel subtraction introduces. Thus,
> where I have added J or H visits of more than 3 and 2 orbits,
> respectively, we may not need to increase the number of references.
> (This decision is very likely to come down to how well the PSF
> NICMOS is expected to be known; Vitaliy is exploring this type
> of question in relation to Albinoni.)
>
> - Greg
>
>
> On Tue, 28 Oct 2003, Robert A. Knop Jr. wrote:
>
> > For each search, we should have for different follow-up possibilities
> > available, to be chosen via TOO. Note that in all cases, the orbit
> > count includes IR final references. Estimates below for R-I are based
> > on the z-J color, *not* on the J-H color. Note that both z and J are
> > contributing to the stretch here.
> >
> > #1 : Low-redshift, no grism needed.
> >
> > 4 orbits in z, spaced as Rachel did
> > 3 orbits in J, spaced as Rachel did
> > 2 orbits in H at the first epoch
> > (save 3 J, 2 H orbits for final ref)
> >
> > TOTAL = 14 orbits
> >
> > WORST CASE z=1.3 (usually we do better!)
> > ds = 0.09
> > dt = 2.5
> > dmbcorr = 0.15
> > d(R-I) = 0.038
> >
> > ==> For a galaxy with a very good photo-z
> >
> > #2 : Low-redshift, grism needed
> >
> > 4 orbits in z, spaced as Rachel did
> > 3 orbits in J, spaced as Rachel did
> > 2 orbits in H at the first epoch
> > 7 orbits grism
> > (save 3 J, 2 H for final reference)
> >
> > TOTAL = 21 orbits
> >
> > Worst case as #1
> >
> > #3 : High-redshift, no grism needed
> >
> > 8 orbits in z, spaced as Rachel did
> > 3 orbits in J, spaced as Rachel did
> > 2 orbits in H at the first epoch
> > (save 3 J, 2 H for final referenced)
> >
> > TOTAL = 18 orbits
> >
> > WORST CASE z=1.5
> > ds = 0.08
> > dt = 2.2
> > dmbcorr = 0.14
> > d(R-I) = 0.046
> >
> > ===> For a galaxy with a very good photo-z
> >
> > #4 : High-redshift, grism needed
> >
> > 8 orbits in z, spaced yadda yadda
> > 3 orbits in J
> > 2 orbits in H
> > (save 3 J, 2 H for final reference)
> > 11 orbits grism
> >
> > TOTAL = 29 orbits
> >
> > Worst case as in #3.
> >
> > -Rob
> >
> > --
> > --Prof. Robert Knop
> > Department of Physics & Astronomy, Vanderbilt University
> > robert.a.knop@vanderbilt.edu
> >
>
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