The ideology of CATS is shortly described in (Trushkin et al., 1996, Verkhodanov et al., 1997). Here we show some details.
We constructed our database in the UNIX operating system
without involving any standard data base systems because of three main
(a) they are very expensive commercial products;
(b) there are no human resources to develope them in ob--
(c) our task is simplier to solve it with complex systems (however, we do not exclude a probability to use such systems in future).
Therefore, we have designed our data base using simple principles, permitting us to include easily new information to our data base system (see Fig. 1):
The catalog description file ( cats_descr) contains the name and type of the catalog (radio, optical, mixed, etc.), frequency range, minimum fluxes or magnitudes, type of coordinates (equatorial or/and galactic), names of the local programs for the select and match functions (both designed in "C" programming language), name of the document file, number of records in the catalog, resolution, calibration factor for obtaining the common scale of flux densities, and the reference.
To simplify the disign of CATS operating programs, two utilites of 'select' and 'match' type have been worked out. These utilites operate with the pattern string, describing a format of the ASCII table with astrophysical data.
A user operates with CATS from any directory since the programs for general use of the catalogs are accessible system-wide.
The described manner of catalog storage eases the database development, its expansion with new data and the fine-tuning of the supporting programs.
All astronomical catalogs have a different format and list different observables. It will be a major challenge to provide uniform access to such a heterogeneous collection of data sets based on different methods, using different notations and units (in the absence of a ``standard'' to create catalogs). Except for parameter-dependent derived quantities, we intend to use all different fields (i.e. columns of data tables) as they were published.
The concept of a ``Reference Directory'' (a central repository of metadata like the descriptions of fields for each catalog, their physical units, mapping of original field names to the actual name in the database, etc), would be extremely important to unify the ``look'' of the catalogs as well as to process user queries.
CATS is capable to accomplish the following tasks:
The result of the object selection can be sent to the standard output or saved in the following formats:
The result of the CATS operation is an 'ASCII'-file sorted according to different object characteristics. It can be used for subsequent investigation of the radio source spectra or statistical source properties in the RATAN--600 data processing system (Verkhodanov et al., 1993).