SIA 2.0 POS parameters

[Walter Landry]

Arnold Rots <arots at cfa.harvard.edu> wrote:
> There is no question in my mind that ICRS and GALACTIC are the basic
> spatial frames that ought to be available.  However, as to the
> server's and the client's role, there is a difference between data
> discovery metadata and data-accompanying metadata.
> 
> I don't think there is any excuse for a service not to keep coordinates
> in its database both in ICRS and in GALACTIC.
> This is a simple matter, both for catalogs and for image (any
> dimensionality) or single location (spectra, light curves) based
> data. That means that any service ought to be able to reply to a
> query in either frame whether it has data available that satisfy the
> query and what those datasets are; and BOX or RANGE queries do not
> cause any problems.

I have a dataset with extremely narrow rows.  Storing both coordinates
would increase storage by 25%.  So I store and index everything in
ICRS and convert as needed to GALACTIC.  Doing RANGE queries in
GALACTIC would be prohibitively expensive.  BOX and POLYGON queries
are fine.

I guess the upshot of this is that I am starting to feel more strongly
that RANGE should be removed from SIA v2.

Cheers,
Walter Landry