This manual describes a library for accessing astronomical catalogs and image servers locally and over the network in a generic way. The basic library consists of a set of C++ classes. In addition, C and Tcl interfaces are provided as well as Itcl widgets for browsing catalogs and catalog hierarchies. There is a separate library module for each of the three interfaces (C++, C and Tcl) and these will be described in more detail later in this document. The cat package described here is organized in the form of a Tcl package that can be loaded dynamically in a Tcl application or linked in as a library.
The main purpose of this library is to provide generic access to a variety of astronomical catalogs available locally or on the network. The interface hides the details of the various catalogs and allows you to access their contents in a uniform way.
The interface libraries provide methods to open and close a catalog, send a query or request and retrieve the results. In addition, methods are available to get information about the catalog contents, such as column names. The C and Tcl libraries are based on the C++ version.
Catalog configuration files contain the information needed to access the catalog servers. These files are specified as URLs (http:/... and file:/...) and so may be local files or automatically downloaded from anywhere on the network. The config files are simple ASCII files that contain
keyword: value
pairs describing each catalog. There are different types of catalog server types, such as
catalog
,
archive
,
imagesvr
,
local
and
dirctory
. The last one is a special type of catalog that points to another catalog configuration file somewhere on the network. In this way, the lists of available catalogs form a tree of catalog severs.
The purpose of this manual is to describe the Astronomical Catalog library interfaces and their implementation.
This document is primarily aimed at software developers using the catalog library package. Some sections are also aimed at those who would like to make catalogs available by developing HTTP catalog servers and making entries in a catalog configuration file. The package is also designed to be of use to ESO VLT applications (via a small layer that adds VLT standard CCS error logging) and to ESO Archive applications. This library is also currently used by Skycat, an astronomical image viewer based on the ESO RTD (Real-Time Display) application. Skycat uses the Tcl interface to provide support for navigating the catalog hierarchy, searching and editing catalogs, and plotting objects at the correct positions in images.
This document is based on the following documents:
[1] VLT-ICD-ESO-17230-0641, 1.0, 08/12/94 -- INTERFACE CONTROL DOCUMENT between Telescope Control Software and "Star Catalog System"
[2] VLT-SPE-ESO-17230-0640, 1.0 06/12/94 -- VLT Software - Requirements on Star Catalog System
[3] VLT-PRO-ESO-10000-0228, 1.0 10/03/93 -- VLT Software Programming Standards
The following documents are referenced in this document:
[ 1] VLT-MAN-ESO-19400-1550 1.0 19/01/98 -- Tcl and C++ Utilities, Programmer's Manual
[ 2] VLT-MAN-ESO-19400-1551 1.0 19/01/98 -- Astronomical Tcl and C++ Utilities
Please send questions or comments to abrighto@eso.org@eso.org.
Copyright © 1998 ESO - European Southern Observatory