A semester-long course on the VO: materials available

[Mark Taylor]

Petr,

On Tue, 20 Aug 2024, Petr Skoda via interop wrote:

> "Why my god you define POINTS and CIRCLES etc .... when you can do cone search
> as (coordinates, radius) in all tools (including SSA) ??" Why 1= ???
> Explaining the flexibiliy of polygons etc .... - no way ....

this at least is improved in ADQL 2.1:

   https://www.ivoa.net/documents/ADQL/20231215/REC-ADQL-2.1.html#tth_sEc4.2.7

For ADQL 2.1 services, the preferred cone search idiom now looks like

   WHERE DISTANCE(t.ra, t.dec, 189, 62) < 0.01

instead of

   WHERE 1=CONTAINS(POINT('ICRS', t.ra, t.dec), CIRCLE('ICRS', 189, 62, 0.01))

and similarly for spatial crossmatch.

Mark

--
Mark Taylor  Astronomical Programmer  Physics, Bristol University, UK
m.b.taylor at bristol.ac.uk          https://www.star.bristol.ac.uk/mbt/