IAU Division III

Previous Guidelines for Cometary Names

These guidelines were in place prior to March 2003, at which time the CSBN approved newer guidelines, now available at this page.

Introduction

All cometary names are subject to the approval of the Committee for Small Body Nomenclature (CSBN), a working group of IAU Division III, in consultation with the IAU Central Bureau for Astronomical Telegrams (CBAT). The following guidelines are the ones that the committee is using in late 1998. The philosophical basis behind the guidelines is to honor discoverers of comets while achieving fairness to the different individuals involved and maintaining reasonable simplicity in both the names themselves and in the procedures. The CSBN can modify these guidelines as it sees fit or decide not to name a particular comet if this seems the best way to achieve the philosophical goals. Deliberations within the CSBN take varying amounts of time. Sometimes a proposed name is almost immediately agreed upon but in other cases, particularly when the full circumstances of a discovery are not communicated immediately to the CBAT, it takes weeks to agree upon a name.

Basic Guidelines

• Comets are generally named for their discoverers, although this need not always be the case. For example a truly bright (and correspondingly rare) comet discovered on the same night by many independent observers would typically not be named for any of the individuals.
• When a discovery is made by a team working together, whether on a single telescope or multiple telescopes, a single name will usually be given to the comet. The discovering team is free to suggest what that single name should be - whether it is a single name or acronym for the entire team or the name of an individual on the team who played a major role in the discovery. It is important that the team consider this at the outset of its search and agree upon how to name the comets found by the team.
• In the case of multiple, independent discoveries, the names of up to three independent discoverers may be assigned, although the actual number of names assigned in a particular case is at the discretion of the CSBN. When multiple names are assigned for independent discoveries, the names will usually be assigned in chronological order of the observations if that is easily and unambiguously determinable. In other cases, the CBAT and CSBN will make a determination of the order that seems most fair.
• Comets for which there are insufficient observations to determine an orbit will generally not be named (these comets receive X/ designations rather than C/ or P/ designations).

Supplementary Discussion and Special Cases

Some additional explanation regarding special cases is appropriate and the following supplementary remarks may make the work of the SBNC more clear.

• Sometimes an asteroid is subsequently discovered to show cometary activity. In this case, the naming depends on numerous factors. If the asteroid has been named, it will retain that name as a comet. If there was reason to suspect a cometary nature, whether from the apparent motion or from a calculated orbit, discovery of the cometary activity would not normally qualify for recognition in the name. If the "asteroid" is singled out for mention on "The NEO Confirmation Page", for example, the likelihood of cometary nature is quite high, and the recognition of the cometary nature would not be credited in the comet's name. If the discovery of cometary nature is not prompted in this way, as would be the case for an object with an orbit in the main belt or some other recognized group of asteroids, then the object will likely be named after both the original discoverer of the asteroidal body and the discoverer of cometary activity (with only one name being contributed from each source). When the discoverer of the (asteroidal) body is a major survey, the survey itself will normally be credited rather than an individual.
• Comets have been named for people who recognized a link between apparitions. While this is still allowed, the committee expects that this will occur very infrequently. Comets with very poorly determined orbits may be accidentally recovered at a second apparition with the link to the previous apparition made only after the fact. In such a case, the CSBN and the CBAT will use their judgement in deciding what constitutes a fair name.
• Exceptions to the rule of a single name per 'discovering team' can be made. However, this will only be considered when there are no other independent discoverers and the exception is well justified. The justification must satisfy the fairness principle, meaning that two names might be considered if it were clear that two people, and only two people, played key roles in the discovery, e.g., one taking an image and the other discovering the comet in the image.
• Numbered, short-periodic comets (P < 200 years) have unique names. Following historical practice, this is achieved by appending serial numbers to the names of short-periodic comets that would otherwise have identical names. Discussions have been taking place about either extending this numbering to all comets or dropping the numbering from all comets but no agreement has been reached. Pending a future decision, the historical practice continues, with the serial numbers being appended when the comet is numbered, usually at its second apparition.

Michael F. A'Hearn
for the CSBN
October 1998

Name Lists

• List for 2000
• List for 2001
• List for 2002
• List for 2003

I'm Tired and I Wanna Go Back to:

IAU .............. IAU Division III ............. IAU CSBN

Department of Astronomy ............. M. F. A'Hearn ............. The Real World