IAU Comet-Naming Guidelines

Comets traditionally receive names based on their discoverers. These guidelines were adopted in 2003 by the IAU Committee on Small Body Nomenclature (now the Working Group on Small Body Nomenclature, WGSBN, under IAU Division F). The Minor Planet Center announces comet names via electronic circulars after reasonable orbits are determined.

Guideline 1: Proper Reporting of Discoveries

1.1. Names are based on information available when the MPC first announces the discovery. The discovery observation is that which permits the MPC to request confirming observations.

1.2. Comets are unavailable for additional discovery claims once the MPC issues a confirmation announcement.

1.3. Independent discoveries reported after the announcement MPEC are usually excluded unless the claim demonstrably predates outside knowledge, the comet remains unnamed, and there are not already two names assigned.

1.4. Discovery time is the first detection or when the discovery image was obtained.

Guideline 2: Regarding Discoverers

2.1. Comets receive names based on individual discoverers' last names when possible.

2.2. Team names may be appropriate. A discoverer detects the comet visually or on photographs/electronic images and communicates accurate position and appearance data. Preferably, limit names to two; more than three should be avoided except for lost comet rediscoveries. Multiple independent discoveries are listed chronologically, separated by hyphens. No more than one name per observing location or program is permitted.

2.3. Very bright comets visible simultaneously to many observers may receive generic names like "Great Comet."

Guideline 3: Teams of Discoverers

3.1. Teams must provide complete and truthful discovery details.

3.2. A "team" is a formally organized group of astronomers with instrumentation seeking celestial objects including comets.

3.3. An acceptable one-word team name or acronym can be used.

3.4. Without a team name, name the comet for the individual finder or leave it unnamed. At most two people from the same program may be credited if: only two team members exist, both were directly involved in discovery and identification, and their surnames differ. Teams with more than two members may use a single observer's name if written testimony confirms they detected and reported the comet. The same name cannot appear twice on one comet.

3.4(b). Comets discovered from publicly published or posted data generally will not receive individual names unless an established program code exists.

Guideline 4: Cometary Nature Not Immediately Noticed

4.1. Objects initially assumed to be minor planets may be discovered to be comets with later observations.

4.2. When a non-discoverer identifies cometary activity or appearance in an "asteroidal" object, both the original discoverer and the identifier may be credited in the comet name, subject to prerequisites: dual recognition occurs only without prior suspicion of unusual nature; if the object appeared on the NEO Confirmation Page or had unusual orbits published beforehand, the identifier is ineligible. The name consists of two parts (the original discoverer and the identifier of thee cometary nature), each limited to one name (individual or team), and team discoverers cannot suggest individual member names.

4.3. Follow-up observers confirming an object is a comet may result in crediting the original discoverer only.

4.4. If a minor planet designation was published before recognizing cometary nature, the comet retains the minor planet designation; otherwise, a new comet designation is assigned.

4.5. Objects receiving permanent minor planet numbers before comet recognition receive dual status, retaining both designations. If already named as a minor planet, the comet inherits that name; otherwise, a new name is assigned following these guidelines.

Guideline 5: Changes in Comet Names

5.1. The MPC/WGSBN may occasionally change rediscovered lost comet names or address spelling/diacritical errors, but such changes are rare.

5.2. Lost short-period comets sometimes are rediscovered after new names are assigned. Names are announced on electronic circulars at first orbital elements publication to maintain stability. When a previously-named lost comet is identified, new names are added to original names.

5.3. New comets later identified with previous "asteroidal" observations do not receive added names after initial publication.

5.4. Prior to name publication, if a new comet matches an asteroidal object reported at the same apparition on multiple nights by a single or team discoverer, both the minor planet designator and discoverer/team name may be credited (total of two names maximum).

5.5. Comet names will not be changed by adding numerals after names where multiple comets share discoverers' names.

Guideline 6: Unnamed Comets

6.1. The WGSBN and MPC reserve the right to delay naming, possibly indefinitely. Reasons include:

• Comets found months or years after observation that are no longer observable (exceptions may be made for team-named sungrazing comets observed by space-based coronagraphs).
• Comets with indeterminable orbits due to poor observations or short observation arcs; These receive X/ designations.
• Disagreement among team members claiming discovery.