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Preparing and Submitting Tabular Data

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The CDS and other astronomical data centers are storing and distributing the astronomical data to promote their usage primarily by professional astronomers. In order to ensure the scientific quality of the data, we therefore require that the data are related to a publication in a refereed journal, either as tables or catalogues actually published, or as a paper describing the data and their context.

In order to facilitate the usability of the data, and to allow their processing by the data centers, we require that:

  1. the data are described accurately enough to allow an unambiguous interpretation of the data, as well as a comprehension of the context in which the data were acquired and/or processed; a single ascii file, named ReadMe, is designed for this role.

  2. the data are in a format which allows their usage by tools currently in usage in our discipline -- normally flat ascii files; other formats can be accepted, but are converted into flat files.

A full description of the standard conventions used for the documentation of the catalogues is available at URL http://vizier.u-strasbg.fr/doc/catstd.htx . The present document just tries to answer to some frequently asked question about how to prepare the data for their inclusion in the Data Center documents. The following topics are covered:


1  How to prepare the Data files

It is assumed that each component of the data set is stored in a file; each file can represent a table, a spectrum (1-D data), or an image (2-D data). As a general rule, plain ascii data files (also called flat files) -- are preferred, simply because such files can always be processed. More explicitely, the following formats can be used:

Therefore: never postscript files, postscript is a language designed for printers, not for storing scientific data !

A short word about file naming conventions: according to ISO 9660 standard, file names are restricted to 8 + 3 characters: 8 characters in the set [a-z0-9_-], followed by a dot and an extension made of 3 characters with the following conventions: .dat for data files, .fit for FITS files, .tex for TeX/LaTeX files, and .txt for text files (ascii files containing only printable text).

Full details about the files and directories structures can be found in the Adopted Standards for Catalogues document.

2  How to fill the ReadMe description file

This file is aimed at describing all data files stored in a catalogued data set, and at providing the necessary explanations and references to the stored material.

All catalogues available at CDS and in associated astronomical data centers have such an associated file, and numerous examples can be found on the FTP directories at CDS.

A full description of the conventions used in this ReadMe file can be found in the Standards for Astronomical Catalogues, and a template is readily accessible for A&A tables. A typical illustration could be e.g. J/A+A/382/389/ReadMe. Short explanations about how to fill the ReadMe file:

3  How to deposit the data

If not too bulky, data files with their ReadMe file can be uploaded from


where some basic checks on the ReadMe and data files are performed. The checking procedure is also available as the anafile package which can be installed with the standard configure and make Linux procedures (man page)

Alternatively, you can:

4  What happens to your data

At the CDS, some checking procedures are executed to verify the compatibility between the data files and their description. This can lead to interactions with the authors, but we are trying to minimize the level of interaction. Once the data are public, they are accessible as plain files in FTP directories at CDS and other participating data centers (e.g. at CfA/Harvard (USA), CADC (Canada), or NOAJ/ADAC, Japan). The data are also added to the VizieR service, with mirrors at CfA/Harvard (USA), CADC (Canada), NOAJ/ADAC (Japan), Cambridge (UK), IUCAA (India), BAO (China).

5  Contacts

For any question related to the preparation of the data, for problems related to non-standard data formatting, or any other difficulty in the management or the transfer of the electronic tables, either send a mail by clicking on the envelope below, or contact directly François Ochsenbein (francois(at)astro.u-strasbg.fr)

©ULP/CNRS - Centre de Données astronomiques de Strasbourg Question@simbad