Data access services provided by the CDS.

The CDS gives access to many astronomical data such as objects, catalogues, images and spectra.

Several services are available to search for and to get these data. Here are the main services:


SIMBAD is an acronym for: Set of Identifications, Measurements and Bibliography for Astronomical Data.

The SIMBAD astronomical database provides basic data, cross-identifications, bibliography and measurements for 18,238,984 astronomical objects outside the solar system.

SIMBAD can be queried by object name, coordinates and various criteria. Lists of objects and scripts can be submitted.

Quickly query SIMBAD:




VizieR provides access to the most complete library of published astronomical catalogues and data tables available on line (25,254 catalogues), organized in a self-documented database.

Query tools allow the user to select relevant data tables and to extract and format records matching given criteria. Specific care has been taken for optimizing access to some very large catalogues such as UCAC2, the USNO-B1, or 2MASS.

Quickly query VizieR:

Gaia DR3 in VizieR

Gaia DR3 in VizieR


Aladin Sky Atlas is an interactive software sky atlas allowing the user to visualize digitized astronomical images, superimpose entries from astronomical catalogues or databases, and interactively access related data and information from the Simbad database, the VizieR service and other archives for all known sources in the field.

Aladin uses the HiPS technology. Presently there are 1,272 HiPS available.


The CDS Portal is a mashup application which aims at:

  • providing a single entry point to search and access the different CDS services, querying simultaneously , and

  • facilitating the workflow between the services

If you want to try it, enter an object name or a position in the text field below.

Quickly query CDSPortal:

Only astronomical objects outside the solar system are supported!


The CDS cross-match service is a tool allowing astronomers to efficiently cross-identify sources between very large catalogues (up to 1 billion rows) or between a user-uploaded list of positions and a large catalogue.

Available tables include 10,000+ VizieR tables and SIMBAD data.

X-Match service

X-Match service


The Sesame queries several databases from the name of an astronomical object (outside the Solar System bodies), and displays some fundamental parameters (J2000 position, type of object).

The databases queried are SIMBAD, NED, and VizieR.

Quickly query Sesame:

M31 in Sesame

M31 in Sesame

Dictionary of Nomenclature of Celestial Objects

Designations of astronomical objects are often confusing. Astronomical designations (also called Object Identifiers) have been collected and published by Lortet and collaborators in Dictionaries of Nomenclature of Celestial Objects outside the solar system.

This Info service is the electronic look-up version of the Dictionary which is updated on a regular basis; it provides full references and usages about 25,691 different acronyms.

MOC Server

The MOC server is a directory service for astronomical resources (catalogues, surveys, databases, etc) provided by members of the International Virtual Observatory Alliance (IVOA). Based on the MOC (Multi-Order Coverage map) standard, it lists resources with spatial and/or temporal coverage (more...).

There are presently 36,404 resources described in this service.