From: Lifan Wang (lifan@panisse.lbl.gov)
Date: Fri Mar 14 2003 - 21:22:30 PST
Just explain why a star which does not have the unfortunate history of
been observed as a supernova at max may have a better chance of getting smaller
errors by increasing the exposure time whereas such luck is impossible for a
supernova that was discovered and observed well at max.
This sort of error correlation is wierd at least, and is in contradiction with
our claims of better statistical treatment of data.
> From robert.a.knop@vanderbilt.edu Fri Mar 14 20:43:48 2003
> To: Lifan Wang <lifan@panisse.lbl.gov>
> Cc: deg@panisse.lbl.gov, deepnews@lbl.gov, hstpaper@panisse.lbl.gov,
> saul@lbl.gov
> Subject: Re: "Error floor"
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> On Fri, Mar 14, 2003 at 01:48:35PM -0800, Lifan Wang wrote:
> > Isn't it true that we plan observations in terms of S/N ratio ? I will be
> > very surprised if anyone is observing the same SN with constant exposure
> > time.
>
> Sure, we increase the exposure time as the flux goes down.
>
> But we don't increase it by a factor of 400 by the time we expect the
> flux to be 5% of its initial value...! That's what you'd have to do in
> order to keep the same magnitude errors all the way down.
>
> Anyway, generally, we talk about the S/N ratio where we use S at peak.
>
> -Rob
>
> --
> --Prof. Robert Knop
> Department of Physics & Astronomy, Vanderbilt University
> robert.a.knop@vanderbilt.edu
>
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