We consider here ``astronomical catalogues'' as static, final compilations of data for a given set of cosmic objects. According to [Jaschek (1989)] they can be further subclassified into (1) observational catalogues, (2) compilation catalogues, and (3) critical compilation catalogues and bibliographic compilation catalogues. In class (1) we also include tables of observational data commonly published in research papers.
The CDS maintains the most complete set of astronomical catalogues in a publicly accessible archive at cdsweb.u-strasbg.fr/Cats.html. Currently ~ 2700 catalogues and published data tables are stored, of which ~ 2200 are available for downloading via ftp, and a subset of ~ 1760 of them are searchable through the VizieR browser (see below). Catalogues can be located by author name or keyword. Since 1993 tables published in Astronomy & Astrophysics and its Supplement Series are stored and documented in a standard way at CDS. As the authors are only recommended, but not obliged, to deposit their tables at CDS, there is a small incompleteness even for recently published tabular material. CDS is also making serious efforts in completing its archive by converting older or missing published tables into electronic form using a scanner and ``Optical Character Recognition'' (OCR) software. However, catalogues prepared in such a way (as stated in the accompanying documentation file) should be treated with some caution, since OCR is never really free of errors and careful proof-reading is necessary to confirm its conformity with the original.
Access to most catalogues is offered via anonymous ftp to cdsarc.u-strasbg.fr in the subdirectory /pub/cats. This directory is further subdivided into nine sections of catalogues (from stellar to high-energy data), and the ``J'' directory for smaller tables from journals. These subdirectories are directly named after their published location, e.g., /pub/cats/J/A+AS/90/327 has tabular data published in A&AS Vol. 90, p. 327.
There are other useful commands on the CDS node simbad which are also available without a ``proper'' SIMBAD account (Section 4.1). You can telnet to simbad.u-strasbg.fr, login as info, give <CR> as password. This account allows one to query the ``Dictionary of Nomenclature of Celestial Objects'' and provides comments on the inclusion (or not) in SIMBAD of objects with a certain acronym. Other useful commands are e.g. findcat, allowing one to locate electronic catalogues by author or keyword, findacro to resolve acronyms of object designations (Section 9), findgsc to search the Guide Star Catalogue (GSC 1.1), and findpmm to search in the USNO-A1.0 catalogue of ~ 5 108 objects (Section 5.2). The commands simbib and simref are useful to interrogate the SIMBAD bibliography remotely (by author's names or words in paper titles) or resolve the 19-digit ``refcodes'' (Section 6). The syntax of all commands can be checked by typing command -help. Users with frequent need for these utilities may install these commands on their own machine, by retrieving the file cdsarc.u-strasbg.fr/pub/cats/cdsclient.tar.Z (~ 40 kb). This allows them to access the above information instantaneously from the command line.
NASA-ADC and CDS maintain mirror copies of their catalogue collections (see the URL adc.gsfc.nasa.gov/adc/adc_archive_access.html). A major fraction of the CDS and NASA-ADC catalogue collection is also available at the Japanese ``Astronomical Data Analysis Center'' (ADAC; adac.mtk.nao.ac.jp), at the Indian ``Inter-University Centre for Astronomy & Astrophysics'' (IUCAA; www.iucaa.ernet.in/adc.shtml, click on ``Facilities''), and at the Beijing Astronomical Data Center (www.bao.ac.cn/) in China.
NASA-ADC has issued a series of four CD-ROMs with collections of the ``most popular'' (i.e. most frequently requested) catalogues in their ftp archive. Some CDs (see adc.gsfc.nasa.gov/adc/adc_other_media.html) come with a simple software to browse the catalogues. However, the CD-ROM versions of these catalogues are static, and errors found in them (see errata at ftp://adc.gsfc.nasa.gov/pub/adc/errors), are corrected only in the ftp archive.
Many tables or catalogues published in journals of the American Astronomical Society (AAS), like the Astrophysical Journal (ApJ), its Supplement (ApJS), the Astronomical Journal (AJ), and also the Publications of the Astronomical Society of the Pacific (PASP), have no longer appeared in print since 1994. Instead, the articles often present a few sample lines or pages only, and the reader is referred to the AAS CD-ROM to retrieve the full data. As these CD-ROMs are published only twice a year, in parallel with the journal subscription, this would imply that the reader has to wait up to six months or more to be able to see the data. At the time of writing neither the printed papers nor the electronic ApJ and AJ mention that the CD-ROM data are also available via anonymous ftp (at ftp://ftp.aas.org/cdrom) before or at the time of the publication on paper. The ftp service appears much more practical than the physical CD-ROMs for active researchers (i.e. probably the majority of readers), and perhaps for this reason AAS has decided that CD-ROMs will not be issued beyond Vol. 9 (Dec. 1997; see also www.journals.uchicago.edu/AAS/cdrom). It would be desirable if readers of electronic AAS journals were able to access the newly published tabular data in their entirety and more directly in the future. With the trend to publish tabular data only in electronic form, there is also hope that authors may be released from the task of marking up large tables in TEX or LATEX , since the main use of these tables will be their integration in larger databases, processing with TEX -incompatible programming languages, or browsing on the user's computer screen, where TEX formatting symbols would only be disturbing (cf. also Section 11).
Most of the AAS CD-ROM data are also ingested in the catalogue archives of CDS and ADC. However, many other catalogues, not necessarily available from these two centres, can be found within various other services, e.g. in CATS, DIRA2, EINLINE, HEASARC, STARCAT (see Section 4.2), or the LANL/SISSA server (Section 6.2), etc.. In particular, the present author has spent much effort to collect (or recover via OCR) many datasets (now almost 800) published as tables in journals (see ftp.astro.ugto.mx/pub/outgoing/heinz/cats.and). About half of these were kindly provided upon request by the the authors of the tables. The others were prepared either via scanning and OCR by the present author, applying careful proof-reading, or they were found on the LANL/SISSA preprint server and converted from TEX (or even PostScript) to ASCII format by the present author. There is no master database that would indicate on which of these servers a certain catalogue is available.