VizieR Help

Output Preferences and Constraint Specifications
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The VizieR Search Page is aimed to set up the desired results: which constraints are to be applied to columns of the tables, which columns will be displayed, and the order in which the records (rows) will be displayed. Once all your wishes are typed in, just click on any Submit Query button – several buttons are provided just to avoid unnecessary scrollings.

Note that existing columns are generally not all presented – but an Adapt Form section proposes different choices for this Selection Page.

Query Setup

This panel permits to choose among several possible presentations, and to set up a few parameters regarding the submitted query.

Maximum Entries per table
defines the maximal number of records that will be returned by the query; this limitation applies to each table, i.e. a query involving four tables may return 200 retrieved rows. Note that there is a default limitation of 9999 entries – see a trick to overcome this limitation in the FAQs.

Output layout
proposes a choice between different presentations of the query results:

ascii tables, are generally displayed much faster than the well-formatted HTML tables. Several options are available concerning the font size, and the links to full records as simple links (the default) or as checkboxes, permitting a display of several full records on a single page;
HTML tables are better formatted and easier to read, but can be very slow to upload and display; in practice, HTML tables containing more than a few hundred rows can hardly be managed by the current browsers
Detailed results display all details of each retrieved row with full explanations; this format will also be very slow in practice when many rows are concerned, and is recommended only when 10 or less rows are displayed.
Tab-Separated-Values (TSV) is a format where the columns are separated by the tab character; this format is generally understood by the spreadsheet utilities. The |-Separated-Values format is quite similar to TSV: the columns are separated by the vertical bar instead of the tab character.
To upload the results into a spreadsheet, just select this Tab-Separated-Values format: the output will not be displayed on your browser, but you can either save the result in a file for later processing, or open it in a spreadsheet application.
the VOTable format is a fully XML-compliant format containing, in a single document, the data as well as the meta-data which describe accurately how to interpret the document. It can be validated against an XML-Schema in the XML-VOTable(xsl) choice, or against a Document-Type-Definition (DTD) in the XML-VOTable(DTD) choice.
the XML-Astrores format is quite similar to VOTable for the metadata part, but the actual data are formatted as tab-separated values, which are easier to process by simple scripts like Perl. It is currently used in the exchanges with the AladinJava applet. Astrores metadata contain a description of the column meaning, the units, the UCDs, the way to access full records, the links to correlated data, etc...
VOPlot opens a plotting tool where the results can be presented in a graphical interactive environment, with a lot of capabilities, and interaction with the AladinJava tool. VOPlot is developped and maintained by our Indian colleagues.
a FITS format (added in April 2001) for the output tables is available (since April 2001). This output format allows to use the fv FITS viewer for e.g. plots, etc.
A SkyCat-compatible output was also added in April 2001; the corresponding cgi-name is /viz-bin/asu-acl followed by the qualifications specified with the ASU conventions.

Output Order
proposes to present the resuts, either in the increasing order of the sorting parameter (e.g. the distance to a designated target), or in the decreasing sequence. The default sorting parameter is the distance to the target is a target was specified, or the original ordering.

Output Positions
The positions of the objects studied in the astronomical catalogues may be found in a large variety of coordinate systems – equatorial coordinates for various equinoxes and epochs, galactic positions, etc. The computed positions allows to present the results in the user's favorite system(s): just check the boxes corresponding to the desired coordinate system. The system entitled Position stands for the system used for the Target definition, i.e. is defined by the menu of coordinate systems in the part of the form dealing with the definition of the Target.

Search by Position

Enter in the Target box a position on the sky in the equinox or reference frame selected. This position may be:

either a position made of RA (right ascension) and Dec (declination) in sexagesimal notation (0 to 24h in RA, -90° to +90° in Dec). Don't forget that RA is made of at least 2 parts (hours and minutes separated by a blank or a colon), and that Dec must start by a + or - sign
or a position made of 2 numbers representing decimal degrees. To be interpreted this way, the numbers must have a decimal point. Therefore,
12 +20 is interpreted as 12^h+20° = 180°+20°, but
12.0 +20 is interpreted as 12°+20°.
or the name of an object, which is converted to a position using Simbad.

The Search Window can be

a circle when the the Radius button is selected;
the surface between 2 circles: just type in the Dimension box 2 numbers representing the minimal and maximal acceptable distance from the center; the 2 numbers must be separated by a blank or a comma.
a rectangular box, with x-axis oriented toward the increasing longitude or right ascension, and y-axis toward the North: just push the Box dimension button, and enter either one number representing the total size of a square box, or two numbers separated by the x sign representing the dimensions of the rectangular box (enter e.g. 4 x 3).
Note that the rectangular surface is parametrized by its total size, and that therefore a 4 x 3 rectangle represents an area smaller that a 2.5 radius circle (the corners of the 4 x 3 rectangle lie on the 2.5 cicle)

The Output preferences for Position checkboxes permit the computation of the checked items for each retrieved result.

Choice of Displayed Columns and of parameter Constraints

This list presents every column of each table; each of the column can be

checked: the column will be included in the result
sorted: the column is chosen as the sorting argument
qualified by a constraint to generate a selection

Note that existing columns are generally not all presented – but an Adapt Form section proposes different choices for this Selection Page.

Qualification Syntax (Contraint Specification)

Qualifying fields is adding one ore more constraints on some of the columns. The qualification syntax follows the ASU protocol:

for character (char) columns: the qualification includes a comparison operator, like == for strict equality or ~ for caseless pattern matching, followed by a comparison value or a pattern
for non-character columns: the qualification includes one or several comparison and logical operators and values.

Some typical examples:

||keep only non-blank (i.e. specified, or not-null) values:  ||  
	!= ||
||restrict a number to the range 12.0 to 12.5:   ||  
	12.0 .. 12.5 ||
||restrict a date to before June 1, 2000:   ||  
	< 2000.06.01 ||
||restrict a stellar spectral type ((char) column) to early types:  ||  
	=*[OBA]* ||

Numeric fields

The following table describes all operators available on numeric fields (i.e. not flagged by (char)):

Operator Meaning Example

= Strict equality (default) =10

!= Inequality !=10

>= Greater or equal >=10

> Strictly greater >10

<= Smaller or equal <=10

< Strictly smaller <10

.. Range of numbers 5..10

+/- Range defined by its mean and semi-amplitude (*) 8+/-2

& AND (logical operator) 1..5 & 7..9

| OR (logical operator) 1..5 | 7..9

, List of values 0,1,2

<<; List of values.
Each value results in a separated table, in a way similar to the output from a list of targets. (**) <<;1;2;3

! NOT (logical operator) ! 1..5

(*) The +/- operator may alternatively be written ± if your keyboard allows this symbol. Note also that for DATE/TIME values, the semi-amplitude can only be given as a number representing decimal days, as e.g. 07-Apr-2001 12:00 ± 3.5 for the days 4 to 10 April 2001 (facility added in April 2001)
(**) since 23/06/2009

Operator	Meaning	Example
=	Strict equality (default)	=10
!=	Inequality	!=10
>=	Greater or equal	>=10
>	Strictly greater	>10
<=	Smaller or equal	<=10
<	Strictly smaller	<10
..	Range of numbers	5..10
+/-	Range defined by its mean and semi-amplitude (*)	8+/-2
&	AND (logical operator)	1..5 & 7..9
\|	OR (logical operator)	1..5 \| 7..9
,	List of values	0,1,2
<<;	List of values. Each value results in a separated table, in a way similar to the output from a list of targets. (**)	<<;1;2;3
!	NOT (logical operator)	! 1..5

Values in Numeric fields

What follows the comparison operators are generally numbers; in a few cases, several ways of writing values are possible:

Type Meaning Example

null Unspecified (blank)value (<0)|null

now Current date and time (DATE only) < now

RA Sexagesimal hours, minutes, seconds of time 23 56 .. 00 04

Right ascension in decimal degrees 359 .. 001

DE Sexagesimal degrees, minutes, seconds of arc +41 45 .. +42 30

Declination in decimal degrees +41.75 .. +42.50

DATE/TIME UT Date and time, alphabetic month >= 1-Jan-1996

UT Date and Time, numeric month >= 1996.01.01 00:00:00

Julian Date >=JD2450083.5

Type	Meaning	Example
null	Unspecified (blank)value	`(<0)\|null`
now	Current date and time *(DATE* only)**	`< now`
RA	Sexagesimal hours, minutes, seconds of time	`23 56 .. 00 04`
Right ascension in decimal degrees	`359 .. 001`
DE	Sexagesimal degrees, minutes, seconds of arc	`+41 45 .. +42 30`
Declination in decimal degrees	`+41.75 .. +42.50`
DATE/TIME	UT Date and time, alphabetic month	`>= 1-Jan-1996`
UT Date and Time, numeric month	`>= 1996.01.01 00:00:00`
Julian Date	`>=JD2450083.5`

Character fields

The following table describes all operators available on character fields (i.e. flagged by (char)):

Operator	Meaning	Example
~	Caseless pattern matching (default)	`~ngc3532`
=	Pattern matching	`=NGC3532`
=~	Caseless equality	`=~ngc`
==	Strict equality	`==NGC`
~\|	\|-separated list of caseless pattern matchings	`~\|Opec\|WR`
=,	comma-separated list of alternatives	`=,HST,IRAS`
=\|	\|-separated list of alternatives	`=\|HST\|IRAS`
!=,	exclusion of a comma-separated list of alternatives	`!=,HST,IRAS`
!~	NOT caseless pattern matching	`!~[obafgkm]*`
!	NOT pattern matching	`![OBAFGKM]*`
!=	Strict inequality	`!=NGC`
>=	Alphabetically greater or equal	`>=A`
>	Alphabetically strictly greater	`>M 51`
<=	Alphabetically smaller or equal	`<=B*`
<	Alphabetically strictly smaller	`< NGC`
<<;	List of values separated by ;(*)	`<<;val1;val2;val3`

(*) (facilities added in June 2009)

Pattern matching symbols

What follows the pattern matching operators (~ = !~ !) is a pattern string which contains the following symbols:

Symbol Meaning Example

[...] One of the characters defined within the brackets =[OBA]*

The - (dash or minus) indicates a range of characters =[A-Za-z]*

[^...] Any single character NOT contained within the brackets =[^OBAFGMN]*

* Replaces 0 to n characters [OB]*

? Replaces 1 character A?C*

Symbol	Meaning	Example
[...]	One of the characters defined within the brackets	`=[OBA]*`
The - (dash or minus) indicates a range of characters	`=[A-Za-z]*`
[^...]	Any single character NOT contained within the brackets	`=[^OBAFGMN]*`
*	Replaces 0 to n characters	`[OB]*`
?	Replaces 1 character	`A?C*`

Note about Heading Blanks: when no operator is listed, the leading blanks (blanks at the left of a character column) are ignored.

joined tables
If you have selected more than 1 table, you can join the tables. See the join documentation.

last update 30 Oct 06:09

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