Catalogue formats

Local catalogues may be stored in several formats. The ``native'' version is called a ``tab separated table'' (TST). This is a simple text file in which the values of the various fields are separated by a single <TAB> character and the catalogue headers are separated from these by a dashed line:

#  comment
keyword1: value1
keyword2: value2

...
ID   <TAB>   RA     <TAB>   DEC   <TAB>  MAG     ...
--           --             ---          ---
OBJ1 <TAB>   210.00 <TAB>   54.00 <TAB>  16.1
OBJ2 <TAB>   210.01 <TAB>   54.01 <TAB>  15.1
....

The usual format of a catalogue is as above, i.e. an object identifier followed by an RA and DEC (in J2000 decimal degrees). Note the <TAB> strings shouldn't be typed in, they are shown explicitly just to make clear where they should be placed. The TST format is also recognised by the CURSA package (SUN/190), which also contains a description of this format.

Additional formats that can be also read and written by GAIA (with a performance penalty) are those supported by the CURSA package (i.e. FITS-tables and STL format) and the ``ASCII_HEAD'' format of the SExtractor/EXTRACTOR package (SUN/226).

The format that is used to open or write a catalogue, is determined by the file extension:

• FITS tables, accepted file types: .FIT .fit .FITS .fits .GSC .gsc
• STL, accepted file types: .TXT .txt
• ASCII_HEAD, accepted file types: .asc .ASC .lis .LIS

All other file extensions are assumed to indicate a TST (the preferred extensions for these are .tab or .TAB).