From: Rachel G. (gibbo@panisse.lbl.gov)
Date: Wed Apr 07 2004 - 12:26:48 PDT
Hi Andy,
I realized this would mean we'd have to think more, as
opposed to using the Pirzkal et al. software in the
straightforward way with the direct image and so forth. We
do have some of Adam's data from last year, and I'd planned
to start figuring out how to deal with it as soon as I'm
back in Berkeley. Vallery Stanishev in Stockholm will also
be working on this.
Have you heard or do you have a sense for how large the
calibration errors that will creep in might get? Because, I
also thought Adam worked in this same mode. He could not
have done all his observations in one Visit. And, as you
know, his results look super.
Ciao,
Rachel
On Wed, 7 Apr 2004, Andrew Fruchter wrote:
> Hi Searchers,
>
> I have just approved visits F0-F5 for observation. However, you should
> know that you are using a very non-standard approach to grism
> observations. You are not taking a direct image in each visit (indeed
> the standard mode takes one associated with each dither position).
> This opens you up to the possibility of sub-pixel shifts between the
> direct image and the grism spectra.
>
> In principle one generally should not need a direct image. One should
> be able to use the zeroth order image (and this could be a more
> accurate way to align spectra in many cases). However, the calibration
> work necessary for this approach to be used has not been done, as far
> as I know.
>
> Cheers,
> Andy
>
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