SIMBAD: How to retrieve information for one object ?


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Chapter 04. How to retrieve information for one object ?

  1. Object identifiers: how to type them
  2. To search all objects around one object


The Web page Identifier query is dedicated to query astronomical objects by their names.

An option list allows several query modes through identifiers:

  • A single identifier
to obtain the data corresponding to an astronomical object. The syntax of an identifier is detailed in this chapter.
  • around an identifier
to obtain all objects within a given radius around the given object (default radius: 10 arcmin.).
  • an identifier template containing wildcard characters
to get all the objects having an identifier matching the given pattern.
  • A whole catalogue
by specifying the catalog name in the main identifier field on this page.

The second form on this page allows to submit a local file containing a list of identifiers. The result can be obtained on the web page, but if it may be large, it is recommended to get it in ASCII format in a file (see the Output Options page for this).

1  Object identifiers: how to type them

The syntax of an identifier is made of two parts:

It is a safe practice to have the catalogue name followed by a space. It can be avoided if the first identifier field begins with a sign, like in a BD number (e.g. BD+08 1432. It can generally be avoided for most identifiers, the parsing of identifiers being quite flexible. Catalogue names are case insensitive.

Examples:
HD 187642     or     HD187642
M 31     or     m31
BD+8 4236     or     BD +8 4236     or     BD +08 4236

Altair, α Aquilae, and RR Lyrae are listed as:
    NAME ALTAIR,     * ALF AQL   and     V* RR LYR
where NAME, *, and V* are the catalogue names.

Many catalog acronyms, defining lists in articles, were designed from the first letters of the three first authors of the paper followed by the publication year. These acronyms are written between brackets (i.e. [VV2003c] for Veron-Cetty+Veron, 2003). Such identifiers can be written without the brackets. They will be automatically added by the software.

Several common usages in designations – which can be sometimes far from the right syntax – are processed by the sesame module. It offers an efficient management of the possible variations in the naming of astronomical objects in SIMBAD and the info database of nomenclature of celestial objects helps to find any allowed designation (see Egret, 1992 and 1993).

The Dictionary of Nomenclature

A list of the catalogue names, abbreviations, or acronyms used (including cluster nomenclature) is available in the Second Reference Dictionary of the Nomenclature of Celestial Objects outside the Solar System (Lortet et al., 1994).

This Dictionary is available on-line, at URL http://astro.u-strasbg.fr/cgi-bin/Dic (see chapter~12).

Specific catalogues

Object names such as Vega and Altair, but also Barnard's star or Crab Nebula, are stored in the database in a specific catalog called NAME, while star names in constellations, such as alpha Lyrae, are stored as catalogue *, and variable stars (R Aquarii) in the catalogue VAR.

You generally can simply type the name (Vega, Altair, or alf Lyrae): the identifier preprocessing module (sesame) will make the internal conversion.

In case of problem, please send a mail at ,   the special hotline account managed by the CDS team.

Naming astronomical objects within SIMBAD: a few hints

Wildcard query

You can query identifiers using wildcards for defining a generic pattern.

Wildcard definitions allow to define string patterns that are checked against actual strings.

Wildcard elements are :

?      represents one character, and exactly one
*      represents any string, even an empty one
[abc]  represents exatly one chararcter among the given list. 
                 Here: a, b or c
[A-Z]  represents one character in the defined range. Here: A to Z
[^at-z]  represents one char not in the given list. Here: any char
                   except 'a' and 't' to 'z'.

An arbitrary string containing at least one char can be represented by ?*.

Examples:

hd *1  retrieve all objects in the HD catalog ending with 1
hd *[abc]  retrieve all objects in the HD catalog ending with a,b or c
            (extrasolar planets).
hd 123?  retrieve the hd numbers from hd 1230 to hd 1239

Such queries can be quite long (a few minutes), mainly because the DBMS doesn't always make use of indices when querying through patterns.

It can be useful when doing such queries which return list of objects driven by an acronym query to impose a particular catalog in the display: on the Output Options , select on the identifier line, from catalog list => and write one (or more) catalog names in the next field.

2  To search all objects around one object

It may be useful to search all objects, in the database, around a given object. This is done by typing an identifier and selecting around this object.

The result is the list of objects, including the queried one, located within the given radius and sorted by increasing distance to the original object.


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