DOKK / manpages / debian 13 / stilts / stilts-mocshape.1.en
STILTS-MOCSHAPE(1) Stilts commands STILTS-MOCSHAPE(1)

stilts-mocshape - Generates Multi-Order Coverage maps from shape values

stilts mocshape [ifmt=<in-format>] [istream=true|false] [in=<table>] [icmd=<cmds>] [order=0..29] [coords=<expr>] [shape=point|circle|polygon|moc-ascii|uniq|stc-s] [mocfmt=ascii|fits|json|raw|summary|cds_ascii|cds_json|cds_fits] [mocimpl=auto|cds|bits|lists] [out=<out-file>]

mocshape takes a list of sky positions or shapes from an input table and generates a Multi-Order Coverage map (MOC) that describes the union of their coverage on the sky.

It does a similar job to the older pixfoot command, but it can cope with input shapes that are more general than just points or circles; it also understands polygons, STC-S strings and other MOC or UNIQ specifications. It is also implemented using some different and more flexible code. It offers more output options for the calculated MOC via the mocfmt parameter, and a choice of MOC construction implementations via the mocimpl parameter. In most cases you can ignore this flexibility, but performance characteristics may be different for the different choices, and it may be worthwhile to experiment when working with very large tables.

See also the Coverage class for MOC-related functions.

Specifies the format of the input table as specified by parameter in. The known formats are listed in SUN/256. This flag can be used if you know what format your table is in. If it has the special value (auto) (the default), then an attempt will be made to detect the format of the table automatically. This cannot always be done correctly however, in which case the program will exit with an error explaining which formats were attempted. This parameter is ignored for scheme-specified tables.

If set true, the input table specified by the in parameter will be read as a stream. It is necessary to give the ifmt parameter in this case. Depending on the required operations and processing mode, this may cause the read to fail (sometimes it is necessary to read the table more than once). It is not normally necessary to set this flag; in most cases the data will be streamed automatically if that is the best thing to do. However it can sometimes result in less resource usage when processing large files in certain formats (such as VOTable). This parameter is ignored for scheme-specified tables.

The location of the input table. This may take one of the following forms:

  • A filename.
  • A URL.
  • The special value "-", meaning standard input. In this case the input format must be given explicitly using the ifmt parameter. Note that not all formats can be streamed in this way.
  • A scheme specification of the form :<scheme-name>:<scheme-args>.
  • A system command line with either a "<" character at the start, or a "|" character at the end ("<syscmd" or "syscmd|"). This executes the given pipeline and reads from its standard output. This will probably only work on unix-like systems.

In any case, compressed data in one of the supported compression formats (gzip, Unix compress or bzip2) will be decompressed transparently.

Specifies processing to be performed on the input table as specified by parameter in, before any other processing has taken place. The value of this parameter is one or more of the filter commands described in SUN/256. If more than one is given, they must be separated by semicolon characters (";"). This parameter can be repeated multiple times on the same command line to build up a list of processing steps. The sequence of commands given in this way defines the processing pipeline which is performed on the table.

Commands may alternatively be supplied in an external file, by using the indirection character '@'. Thus a value of "@filename" causes the file filename to be read for a list of filter commands to execute. The commands in the file may be separated by newline characters and/or semicolons, and lines which are blank or which start with a '#' character are ignored. A backslash character '\fR' at the end of a line joins it with the following line.

Maximum HEALPix order for the MOC. This defines the maximum resolution of the output coverage map. The angular resolution corresponding to order k is approximately 180/sqrt(3.Pi)/2^k degrees (3520*2^-k arcmin). Permitted values are 0..29 inclusive. The default value is 10, which corresponds to about 3 arcmin.

Name of the column or an array expression giving the coordinates of the shape in each row to add to the MOC. The type and semantics of this value (the type of shape represented) are defined by the shape parameter.

Defines the interpretation of the coords parameter, i.e. the type of shape defined by the supplied coordinates.

The options are:

  • point: 2-element array (ra,dec)
  • circle: 3-element array (ra, dec, r)
  • polygon: 2n-element array (ra1,dec1, ra2,dec2,...); a NaN,NaN pair can be used to delimit distinct polygons.
  • moc-ascii: Region description using ASCII MOC syntax; see MOC 2.0 sec 4.3.2. Note there are currently a few issues with MOC plotting, especially for large pixels.
  • uniq: Region description representing a single HEALPix cell as defined by an UNIQ value, see MOC 2.0 sec 4.3.1.
  • stc-s: Region description using STC-S syntax; see TAP 1.0, section 6. Note there are some restrictions: <frame>, <refpos> and <flavor> metadata are ignored, polygon winding direction is ignored (small polygons are assumed) and the INTERSECTION and NOT constructions are not supported. The non-standard MOC construction is supported.

If a blank value is supplied (the default) an attempt will be made to guess the shape type given the supplied coordinate column; if no good guess can be made, an error will result.

Determines the output format for the MOC file.

Controls how the MOC is built. You can generally leave this alone, but if you find performance is slow, or you are running out of memory, it may be worth experimenting with the options.

  • auto: Chooses implementation based on order
  • cds: Uses CDS SMoc class
  • bits: Uses BitSets
  • lists: Uses BitSets and lists

The location of the output file. This is usually a filename to write to. If it is equal to the special value "-" the output will be written to standard output.

stilts(1)

If the package stilts-doc is installed, the full documentation SUN/256 is available in HTML format:
file:///usr/share/doc/stilts/sun256/index.html

STILTS version 3.5.2-debian

This is the Debian version of Stilts, which lack the support of some file formats and network protocols. For differences see
file:///usr/share/doc/stilts/README.Debian

Mark Taylor (Bristol University)

Mar 2017