How to refer to a source or designate a new one

from the IAU Commission B2 Working Group on Designations
(for astronomical sources of radiation outside the solar system)

Current chair: Marion Schmitz

(version August 2018)

Source listings should always contain positional information and/or a second designation in order to avoid ambiguities which can arise with a single designation.

Existing designations, when used in listings, should not be altered and for rarely used names a bibliographical reference for the designation should be given.

When creating a new catalogue of sources, please consider registering for an acronym, preferably before your new objects become referenced (even informally).

When creating new designations, such as for newly discovered source(s), the following procedure is recommended:

  1. Think up an acronym of at least three characters and check the online Interactive Dictionary of Nomenclature to be sure your acronym is unique.

  2. Think up a sequence numbering
    • running number, or
    • based on the position, e.g. a chain based on truncated 2000 coordinates preceded by the letter J (example: J1234+5612)

Other examples and rules are in the IAU Recommendations for Nomenclature, including helpful hints.

Consult representatives of the Working Group Designations if problems arise and specific advice is desired.


World-Wide-Web access to the Interactive Dictionary of Nomenclature is managed by the Centre de Données de Strasbourg (CDS) at the URL address:; mirror installations are available at

Working Group Designations
Advice on specific problems may be obtained from members of the representatives of the Working Group on Astronomical Designations of IAU Commission B2 (current chair, Marion Schmitz), see the list at the end of the IAU Recommendations for Nomenclature.