STILTS-MOCSHAPE(1)

📦
version 3.5.4 · 2 versions
, in ubuntu stonking

💖 NAME 💖

stilts-mocshape — bestie, this one makes Multi-Order Coverage maps out of shape values ✨

🌈 SYNOPSIS 🌈

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>]

🦋 DESCRIPTION 🦋

okay so mocshape takes a whole list of sky positions or shapes from an input table and generates a Multi-Order Coverage map (MOC) — which is literally just a description of the union of their coverage on the sky 💅

It's doing a similar job to the older pixfoot command, but the way it ate is that it can cope with input shapes way more general than just points or circles. It also gets polygons, STC-S strings, and other MOC or UNIQ specifications. Not only that, it's implemented using some different and more flexible code, bestie 🫶

It serves up more output options for the calculated MOC via the mocfmt parameter, and you get a choice of MOC construction implementations via the mocimpl parameter. Most of the time you can just ignore all that flexibility, no cap — but the performance characteristics may be different for the different choices, so it may be worth experimenting when you're working with very large tables 👑

Also, go look at the Coverage class for MOC-related functions, iykyk.

✨ OPTIONS ✨

  • ifmt=<in-format> — Tells it what format your input table is in, as specified by the in parameter. All the known formats are listed in SUN/256. Use this flag when you already know what format your table is, periodt. If it's set to the special value (auto) (which is the default), then it'll try to detect the format automatically. The thing is, that can't always be done correctly, and if it can't, the program exits with an error explaining which formats it attempted 😭 Just so you know: this parameter is ignored for scheme-specified tables.
  • istream=true|false — Set it true and the input table specified by the in parameter gets read as a stream. You must give the ifmt parameter in that case, fr fr. Depending on the required operations and processing mode, this may cause the read to fail (sometimes it's necessary to read the table more than once, and that's just how it is). It's not normally necessary to set this flag — in most cases the data will be streamed automatically if that's the best thing to do 💅 But sometimes it can result in less resource usage when processing large files in certain formats (like VOTable). This parameter is ignored for scheme-specified tables.
  • in=<table> — Where your input table lives. It can take one of these 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, ngl.
    • 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. Slay.

  • icmd=<cmds> — Specifies processing to be performed on the input table as specified by the in parameter, 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 you're giving more than one, separate them with 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 you give 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 '@'. So 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.

  • order=0..29 — The maximum HEALPix order for the MOC. This is what 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.
  • coords=<expr> — 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 (i.e. the type of shape represented) are defined by the shape parameter.
  • shape=point|circle|polygon|moc-ascii|uniq|stc-s — Defines the interpretation of the coords parameter, i.e. the type of shape defined by the supplied coordinates.

The options, bestie:

  • 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. Heads up: 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 💀

  • mocfmt=ascii|fits|json|raw|summary|cds_ascii|cds_json|cds_fits — Determines the output format for the MOC file. Simple as that 💖
  • mocimpl=auto|cds|bits|lists — Controls how the MOC is built. You can generally leave this alone, lowkey, 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
  • out=<out-file> — 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 👑

👀 SEE ALSO 👀

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

🌸 VERSION 🌸

STILTS version 3.5.4-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

🎀 AUTHOR 🎀

Mark Taylor (Bristol University)

and that's the whole vibe, bestie — this page is from Mar 2017, it's part of STILTS-MOCSHAPE(1) in the Stilts commands manual, and yeah, the source is STILTS 3.5.4-debian. go make some coverage maps 🫶✨💅

📦 where this page comes from