The form in the first page accepts three different types of input and
combines them to return a list of matching catalogs; in addition,
output options can be specified here (in the VizieR navigation bar )
These types of input are:
In addition, lists of catalogs (by acronyms, dates, popularity, etc...)
can be retrieved from the links at the bottom of the form.
While you are filling the form, an estimation of the number of
matching catalogs is shown near the bottom of the form (in green
at the left of the Find Catalogs button).
1 The target input
It is composed of the following elements:
- the target box, where is it possible to enter
either a source name (e.g. NGC 4321)
which is converted into its position on the sky by Sesame;
or a celestial position as
2 coordinates (e.g. 12 22 54.9 +15 49 21) or
a so-called IAU-position (e.g. J122254.9+154921);
- the type of coordinates (J2000, Galactic, etc.) – only useful
if a set of 2 coordinates are typed in;
- the target dimension (may contain 2 numbers separated by a
comma or the letter x) with its unit;
- the geometry of the target: a circle or a box.
In the case of a box, the target dimension represents the size
of a side of the box (2 numbers in the target dimension
define a rectangle, e.g. 2x4). In the case of a
circle, the number represents the radius of a circular target,
and 2 numbers (e.g. 2,4) represent the surface
around the target within the 2 circles having the specified radius.
A last button Find Data will display all results of the
2 The keyword input
This possibility cimbines a free-text input (the left part)
a list of keywords (the right part).
- In the free text input, you may enter:
- a catalog designation as:
- either a usual acronym or abbreviation like
NGC, HIP, USNO2, etc...
(see the full list of acronyms known in VizieR)
- or by the unique designation of catalogs
used by CDS/ADC like
I/239 or 1239 assigned to the Hipparcos
catalogues, or J/A+A/275/101 for the tables
associated to the publication in
A&A 275, 101
(full list of Designations
known in VizieR).
The designation may specify a unique table,
like VII/258/vv10 which represents the table
of confirmed quasars, BL Lac and AGNs
in the Véron and Véron compilation of quasars
(13th Ed., 2010).
- several catalogues can be entered, separated
by blanks or commas, like
the Tycho-2 and the USNO-A2 catalogues.
- the * (asterisk) can be used as a wild card,
and you may for example get all catalogues of the
IX category (high-energy catalogues)
- free words like authors, title, description, etc.
You may enter
one or several words which are simultaneously found
in a short description of the catalogue, which includes
author's names, the title, and a short summary.
For instance, typing
cfa redshift will locate
catalogues quoting these two words in any order.
- words made of 1 or 2 letters are
normally ignored (there are a few exceptions,
like IR or UV)
- only the first 7 characters of a word are significant;
- common words (like and, are, etc) are
- the plural in words should be avoided
(use galaxy, not galaxies)
if the text represents a catalog or an acronym, the result will
be limited to the catalog or the set of catalogs known by that
acronym. It is possible to override this default behaviour
by checking the Expand search box, to get back the catalogs
found from a standard textual search
- a list of predefined keywords is proposed.
These keywords are presented in 3 categories:
- keywords related to the wavelength;
- keywords related to the Mission
(results gathered by astronomical satellites and rockets)
- keywords related to astronomical data
Within each of the 3 keyword lists,
the selected items are ored,
which means that e.g. selecting simultaneously
Radio and IR items in the leftmost category will restrict
the choice to catalogues dealing with Radio data or
(some browsers require to push down the Control
key to remove one item or to select several items)
The choices specified in each of the 3 keyword lists are anded,
which means that choosing keywords e.g.
X-ray in the leftmost box,
Rosat as a Mission name,
and Galaxy in the rightmost box,
will locate catalogues observed in the
X-ray waveband, with the Rosat satellite,
and dealing with galaxies. Entering qualifications in several
of the proposed boxes will therefore rapidly result in an empty set.
3 The columns contents input (UCD)
This section of the form is opened by a click on the
Search catalogs by column descriptions link.
This selection is based on a description of the contents of a
catalog by a Unified Content Descriptor
The goal is to search catalogs containing the type of data (or columns)
you are interested in.
It is made of two parts:
- the top part contain a text field. Write your UCD or fill it using the bottom part.
the UCD is written as a list
of 1, 2 or 3 entity separated by a semi-colon (;)
(note that the order of the entities is important);
each entity is a made of one or several words
separated by a dot (.)
describing the logical view that you can see when you choose the
UCD tree option.
So, a UCD may be defined by:
UCD = entity[;entity[;entity]]]
The asterisk (*) iis interpreted as a wild card
to include a set of UCDs or entities.
- alternatively, the bottom part can be used
to search for UCDs without any
knowledge of the UCD syntax.
Three forms are available (you can switch from one to another with the radio buttons):
- Simple examples is a short list of common types of columns.
- Textual search displays (when a blank is typed or the Enter
key is pushed on the field)
a list of UCDs known in VizieR which match
- UCD tree is the hierarchical view off all UCD elements.
The UCDs may be combined with the logical operators or (|)
and (&). By default (no operator specified), the UCDs
and anded (combined with the & operator).
|arith |specifies all columns which have UCD including the
entity (ie: [*;]arith[;*])|
|arith* |specifies all columns which have UCD including the
word (ie: [*;]arith*[;*],
include all entities arith.*)|
|+phys.veloc;src.redshift;pos.galactic |specifies only columns which have this UCD.|
|phys.veloc;*;pos.galactic |is a set of UCDs matching the a formatted type.
4 Browsing Modes
This last way of finding catalogues consists in a few lists of the
catalogues ordered in different ways. A Self-Organizing Map
(also known as Kohonen map
) is an application of the neural network techniques, and offers
another view of the set of catalogues.
last update: 18 Feb 07:12