The generic URL used in ASU follows the generic rules of the HTTP protocol (RFC 1945):
http://root_URL?arg1&arg2&...where the ampersand &) separates the arguments when there is more than a single argument. The HTTP protocol also specifies that any special character (blank, quotes, and + * < > & # ) exsiting in an argument should be encoded by a percent sign (%) followed by its ascii hexadecimal representation. The blank must therefore be replaced by %20, the + sign by %2b, etc.
The root URL to get results from VizieR is
In the root URL, the host name (vizier.cds.unistra.fr) may be replaced by one of the mirrors: vizier.ast.cam.ac.uk, vizier.cfa.harvard.edu, vizier.hia.nrc.ca, vizier.nao.ac.jp, vizier.iucaa.ernet.in, vizier.inasan.ru, vizier.bao.ac.cn, vizier.ukirt.jach.hawaii.edu.
Following the question mark (?), the ASU arguments are written in the general form name=value The following conventions about name are used:
Specifying a Choice of Catalogues: there are several ways of designating catalogues; the fastest is to use the catalog identification assigned in VizieR like -source=I/239/hip_main for the main Hipparcos catalog.
||-source= ||catalog(s) to query (Several catalogs may be specified if separated by a comma or a blank).
Well-known catalog abbreviations may be used – the full list of abbreviations known in VizieR can be listed.|| ||-words= ||names or words of title of catalog. The words are and'ed, i.e. only the catalogues characterized by all the words are selected.|| ||-kw= ||keyword in any of the 3 lists by Wavelength, Mission, or Astronomy.
If several keywords are given on the line, they are or'ed; but if several lines with -kw=value exist, their content is and'ed.|| ||-ucd= ||designation of UCD
The catalogues having one or more columns matching the specified UCD(s) are selected; the * may be used as a wild character, e.g. PHOT_*_B represents a blue photometry which can be in a lot of different photometric systems.
Several -ucd=value can be used to select catalogues having simulteously the properties specified by the UCDs; in other terms, similalry to -kw, UCDs specified on the same line are or'ed, while the different lines are and'ed.|| ||-pos ||restricts to tables containing celestial positions|| ||-phot ||restricts to tables containing well-defined photometry|| ||-nosurvey ||restricts the choice to catalogues outside the ``survey'' list of catalogues.|| ||-obsolete ||asks to include the obsoleted versions of catalogues in the set.|| ||-corr= ||correlation for a fine-grain selection of tables:
-corr=pos restricts to tables having a position; -corr=name=col_name restricts to tables having the specified col_name among its columns; -corr=PK=col_name restricts to tables having the specified col_name and this column is a primary key of the table; -corr=FK=col_name restricts to tables having the specified col_name and this column is a foreign key of the table;
Target Center: the specification of a target requires a center – a position in the sky – and a geometry around the center. Only a circle/annulus, and a rectangular box, are available.
||-c= ||defines the center of the target
There are many possibilities of specifying the center – by object name, position in sexagesimal or decimal degrees. For equatorial positions, remember that a sign must exist before the declination, and that no decimal point in the RA part implies a sexagesimal position (i.e. 15 +12 means 15h+12°, but 15.+12 means 15°+12°, or 1h+12°.|| ||-c.eq= ||defines the equinox of the position given in the -c argument. Note that this parameter is not useful when the target is specified by a name.
Typical examples are -c.eq=B1950 or -c.eq=Gal
The default is -c.eq=J2000|| ||-c.rm= ||defines the radius of the target in arcminutes.
Two numbers may be specified: in the case, the target is an annulus.|| ||-c.rd= ||defines the radius of the target in degrees.|| ||-c.rs= ||defines the radius of the target in arcsec.|| ||-c.bm= ||defines a rectangular box of horizontal/vertical dimensions in arcmin, as e.g. -c.bm=8x6|| ||-c.bd= ||defines a rectangular box in degrees|| ||-c.bs= ||defines a rectangular box in arcsec.|| ||-box= ||defines a rectangular box using IAU-conventions, e.g. J0000-00 for a box in J2000 coordinates containing the positions having their RA between 0h0m and 0h1m and their declination between 0° and –1° This convention is valid also with other coordinate systems: Bhhmm...±dd... (B1950 position), Glon...±lat... (galactic position), S... (supergalactic) and E (ecliptic).
Finally a box may also be represented by a qbox value, the systems of cells used to access by positions (described briefly in the qbox man page)||
Output Contents: the contents and order of the result can be specified by the following arguments:
||-meta ||No actual query is performed, only the tables involved in the query are described. This is useful to get an idea of which catalogues exist which share e.g. a keyword. || ||-meta.all ||similar to -meta, but all metadata (details of columns) are listed.|| ||-meta.max= ||specifies the maximal number of catalogs to be listed (the default is 500) || ||-out= ||specifies the result columns to list in the output; -out= is normally followed by a list of column names (separated by blanks) to be displayed.
The list may contain, in addition to standard column names:
||_r ||Distance from the target center || ||_x ||Horizontal distance from the target center (East)|| ||_y ||Vertical distance from the target center (North)|| ||_pa ||Position angle (North through East) of vector from the target center (degrees)|| ||_key ||The column representing a key (identifier) of a row (typically the recno counter when that one exists) || ||_ID ||a string which identifies a row, in the form name=value (typically recno=record_counter)|| ||_RA(Equinox, Epoch) ||Computed right ascension for a specified frame / equinox / epoch with the standard conventions: ICRS represents the ICRS frame, J2000 represents the FK5(J2000)/ICRS frame, and B1950 the FK4(B1950) frame.
_RA _RAJ or _RAJ2000 are a shorthand for _RA(J2000,J2000)
_RAJ() is a shorthand for _RA(J2000) (keeping the epoch)
_RAB or _RAB1950 are a shorthand for _RA(B1950,B1950). || ||_DE(Equinox, Epoch) ||Computed declination, using the same conventions as _RA || ||_GLON ||Computed galactic longitude || ||_GLAT ||Computed galactic latitude || ||_SGLAT ||Computed supergalactic latitude || ||_SGLON ||Computed supergalactic longitude || ||_1 ||Name of target or input constraint (applies to lists) || ||_q ||Counter (from 1) of target number (applies to lists) || ||_V ||A http link to the row being edited. _V may be followed by a text which will be used in the link. || ||_sed0 ||Minimal details to build an SED (Spectral Energy Distribution): edit the columns containing magnitudes or fluxes in well-identifier filters, wavelengths or frequencies. || ||_sed1 ||In addition to _sed0, compute the flux (in Jy)|| ||_sed3 ||Present the SED as 3 vectors: (1) frequencies (GHz), (2) fluxes (Jy) and (3) errors on fluxes (Jy) || ||_sed4 ||Present the SED as a set of formatted SED points; one point is formatted as GHz=Jy[errJy]${col}[filter] e.g. 241.77e+3=31.3[0.8]e-3${Jmag}[2MASS:J] for a flux in the 2MASS J-band, or 353.00=8.91[0.21]${S}@{Freq} for a flux from the column S and the frequency from the column Freq. ||
||h ||(header) add the column names || ||u ||(unit) add the units of each column || ||U ||(UCD1) give the UCD1 (default is UCD1+)|| ||2 ||(2UCDs) give the two UCDs (UCD1 and UCD1+)|| ||D ||(Description) adds the description of columns || ||L ||(Links) add the definition of Links (may result in more columns than what was asked)||
||DTD ||(for VOTable output): use the DTD definition rather than the standard XML-Schema || ||bin64 ||(for VOTable output): use a binary 64-encoded output for the data || ||TSV ||(for VOTable output): use a Tab-Separated-Values representation of the data (the Astrores way) || ||groups ||(for VOTable output): use the groups of columns introduced in VOTable1.1|| ||mini ||(for lists): minimize the output, i.e. keep a single table which gathers the results of the list (the list must be applied to a single table) |||| ||-sort= ||Sort order, e.g. -sort=_r to sort by increasing distance to the target. A minus sign before the column name (e.g. -sort=-_r) indicates a decreasing order.|| ||-oc.form ||form of the computed position, as -oc.form=d for decimal degrees, or-oc.form=s for sexagesimal representations. An optional M (Main) can be added to specify that the UCD qualification main main is added to the computed position (by default this main qualification is attached to the original position) ||
Joining tables: Two or more tables can be combined or joined into a single table; some details and examples can be found in the join documentation. The following argments are specific to joins:
||-joincol ||specifies the column used in the join (the name must be shared among the tables involved).|| ||-outjoin ||specifies the table.column of the referent column in the case of outer joins.||
Issuing several queries: Independant queries can be issued in a single request, using a -go separator. More control can be specified in the case of votable output: