Gravitational Lens, Ontological Dispersion.

[Bernard Vatant]

http://cfa-www.harvard.edu/castles/index.html

A good illustration of some typical ontological issues discussed lately.
... could provide a good test bed for any tool you could think about ...

What objects are classified here?

-- The title of the page is : "Gravitational Lens Data Base"
-- The presentation says : "We will provide information and data on gravitational lens
systems".
Follows a table of "Multiply Imaged Systems" including a chilling grade system :(
"... likelihood that the object is a lens:
A=I'd bet my life, B=I'd bet your life, C=I'd bet your life and you should worry."

Take one of the "objects" classified here, say "PG 1115+080" - Grade A, not a too risky
one :)
PG 1115+080 is the "Lens Name" ("standard name for the lens"). So far, so good ...

But look at the reference papers to find out various types for the same guy ...

 -- Gravitational Lens
 -- Galaxy Lens
 -- Gravitational Lens System
 -- Quadruply Imaged Quasar
 -- Quadruple Gravitational Lens
 -- Gravitational Mirage
 -- Multiple QSO
 -- Triple QSO

So what does PG1115 + 08 identifies?

-- The (set of) QSO(s) of which image is distorded?
-- The massive system (galaxy?) provoking the lens effect?
-- The system "QSO + lens"?
-- The whole region of space-time where the lens effect takes place?
-- The apparent source(s) on the sky?

-- All of those, in different scopes?

And if it's only one of those, what are the identifiers for the others, if necessary?

In short, what are the data at
http://cfa-www.harvard.edu/castles/PG1115.html
exactly about?

Looks like the lens effect is also provoking some ontological dispersion ;-)

Is Virtual Observatory Semantics supposed to tackle that kind of issues?

Bernard