Scope of registry

[Alex Szalay]

Thanks for comment -- I fully agree. Which brings up the need of
(possibly) a third method, that of survey.contains(POINT p).

This could either return a TRUE/FALSE, or even a fuzzy number for 
a redshift survey (see 2dF), equal to the sampling probability.


Cheers, ALex

-----Original Message-----
From: owner-metadata at us-vo.org [mailto:owner-metadata at us-vo.org]On
Behalf Of Clive Page
Sent: Wednesday, February 05, 2003 12:49 PM
To: Arnold Rots
Cc: registry at ivoa.net; metadata at us-vo.org
Subject: Re: Scope of registry


On Wed, 5 Feb 2003, Arnold Rots wrote:

> At issue is the question how "potentially" should be defined.

Just to clarify one point arising from Alex Szalay's comments and yours -
I don't think it is necessary for detailed information to be held in the
Registry, as the best answer the Registry can give the user as to whether
a given resource has the required information are just

 - no
 - maybe

(because the answer "yes" implies a degree of certainty which the
Registry, with its somewhat high-level view of metadata, can never have).

So the spatial information in the Registry does not need to be concerned
with exact edges, or chip boundaries, or other fine details, just enough
to know whether the field was probably covering the (RA,DEC) of interest.

It would still be useful to know whether one was within the typical field
radius of the centre of some HST observation (if one were interested in


-- 
Clive Page,
Dept of Physics & Astronomy,
University of Leicester,    Tel +44 116 252 3551
Leicester, LE1 7RH,  U.K.   Fax +44 116 252 3311