Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quadruply-imaged quasars: some general features   Gravitational lensing of point sources located inside the lens caustic is
known to produce four images in a configuration closely related to the source
position. We study this relation in the particular case of a sample of
quadruply-imaged quasars observed by the Hubble Space Telescope (HST). Strong
correlations between the parameters defining the image configuration are
revealed. The relation between the image configuration and the source position
is studied. Some simple features of the selected data sample are exposed and
commented upon. In particular, evidence is found for the selected sample to be
biased in favour of large magnification systems. While having no direct impact
on practical analyses of specific systems, the results have pedagogical value
and deepen our understanding of the mechanism of gravitational lensing.

20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph