TIMERES & SPATRES?

[Doug Tody]

Hi Randy -

(I hope you don't mind if I copy this to the DAL list as I think this
is subtle enough to benefit from broader comment).

TIMERES is probably a lot more important for time series data than
for spectra.  For a time series, it refers to the smallest feature
which can be resolved (in the time coordinate) in the time signal
being sampled.  For an image or spectrum, I suppose it would refer
to the extent (stop-start) of the exposure in time.  This is possibly
still a useful thing to know, even for a spectrum.

SPATRES, since it refers to the spatial resolution rather than the
spatial sampling, is probably better defined as a measure of the spatial
PSF of the field observed by the spectrograph.  This is usually related
to the aperture size, but not necessarily (there is no way to query on
the aperture size, but this information should come back in the query
response metadata and the query can then be refined by the client).

There is also SPECRES, which will probably be renamed SPATRP and will
refer to the resolving power of the spectrum or instrument rather
than the resolution.

 	- Doug


On Mon, 29 Jan 2007, Randall Thompson wrote:

> Hi Doug,
>  Can you explain the TIMERES and SPATRES query parameters
> in a little more detail? Does TIMERES refer to the total
> exposure time, and is SPATRES the spatial dimension of the
> aperture, (or more correctly, the extraction slit)?
>  Sorry if I asked this before. We are trying to decide
> if we can support these optional parameters.
>
> Randy
>