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5.2.1 Input Formats

Some of the tools in this package ask you to specify the format of input tables using the ifmt parameter. The following list gives the values usually allowed for this (matching is case-insensitive):

FITS format - FITS binary or ASCII tables can be read. For commands which take a single input table, by default the first table HDU in the file will used, but this can be altered for multi-extension FITS files by supplying an identifier after a '#' sign. The identifier can be either an HDU index or the extension name (EXTNAME header, possibly followed by "-" and the EXTVER header), so "table.fits#3" means the third HDU extension, and "table.fits#UV_DATA" means the HDU with the value "UV_DATA" for its EXTNAME header card.
Column-oriented FITS format. This is where a table is stored as a BINTABLE extension which contains a single row, each cell of the row containing a whole column of the table it represents. This has different performance characteristics from normal FITS tables; in particular it may be considerably more efficient for very large, and especially very wide tables where not all of the columns are required at any one time. Only likely to be efficient for uncompressed files on disk.
VOTable format - any legal version 1.0, 1.1, 1.2, 1.3 or 1.4 format VOTable documents, and many illegal ones, can be read. For commands which take a single input table, by default the first TABLE element in the document is used, but this can be altered by supplying the 0-based index after a '#' sign, so "table.xml#4" means the fifth TABLE element in the document.
Enhanced Character Separated Values format was developed within the Astropy project and is described at It is composed of a YAML header followed by a CSV-like body, and is intended to be a human-readable format with rich metadata. Most of the per-column and per-table metadata used by STILTS is preserved when de/serializing to this format. STILTS currently supports ECSV 0.9.
NASA Common Data Format. CDF is described at
Feather file format is a column-oriented binary disk-based format based on Apache Arrow and supported by (at least) Python, R and Julia. Some description of it is available at and It can be used for large datasets, but it does not support array-valued columns. It can be a useful format to use for exchanging data with R, for which FITS I/O is reported to be slow.
Plain text file with one row per column in which columns are separated by whitespace.
Comma-Separated Values format, using approximately the conventions used by MS Excel.
Special-interest GBIN format for internal use by the DPAC consortium in relation to the Gaia astrometry satellite. Additional classes (data model and GaiaTools GBIN reader) are required on the classpath at runtime to use this format (e.g. stilts -classpath MDBExplorerStandalone.jar or java -classpath stilts.jar:MDBExplorerStandalone.jar
Tab-Separated Table format, as used by Starlink's GAIA and ESO's SkyCat amongst other tools.
IPAC Table Format.
World Datacentre Format (experimental).
For more details on these formats, see the descriptions in SUN/253.

In some cases (when using VOTable, FITS, ECSV, CDF, Feather or GBIN format tables) the tools can detect the table format automatically, and no explicit specification is necessary. If this isn't the case and you omit the format specification, the tool will fail with a suitable error message. It is always safe to specify the format explicitly; this will be slightly more efficient, and may lead to more helpful error messages in the case that the table can't be read correctly.

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