|| IAU Division III
Committee on Small Body Nomenclature
Comité pour la nomenclature des petits corps
A Committee of IAU Division III
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Guidelines for Cometary Names
Comets did not become routinely named for their discoverers until the
20th century. In the 19th century, names were generally used for
short-period comets only after their second apparition;
single-apparition short-period comets and long-period comets were
generally referred to by designations (with names sometimes, though not
with much consistency, given parenthetically).
In recent years, the comet-naming process has been impacted by
several wide-field CCD surveys conducted by professional teams. It is
therefore appropriate to write down guidelines for the naming of comets to
make the process as simple and fair as possible. Though guidelines have
been drafted previously by IAU Commission 20 members in recent years, this
aims to replace those guidelines by starting anew, by creating guidelines
that are even simpler and more fair. These guidelines may need to be
revised by the CBAT and CSBN, as special circumstances warrant.
The CBAT works closely with the Minor Planet Center (MPC) in many cases
regarding the astrometry, identifications, orbit computing, and collection
of observations. In recent practice, comet names are announced on IAU
Circulars after a reasonable orbit has been determined, in an effort to
prevent re-naming of lost comets. The CBAT consults with the CSBN on
non-routine naming matters, in which some interpretation of the following
guidelines is deemed appropriate.
- Regarding proper reporting of discoveries.
- Comets normally receive their names on the basis of information
available to the CBAT at the time of first official announcement
of the discovery. The discovery observation (and thus the
discoverer) is taken to be that which permits the CBAT to issue
reasonable requests for confirming observations (directly to
individual observers or sometimes via "The NEO Confirmation Page"
at the CBAT/MPC website) or to issue an announcement Circular.
- Comets are generally considered no longer available for additional
recognized discovery claims once the call for confirmation has been
widely issued (e.g., e-mail or World Wide Web posting) by the
CBAT or MPC.
- Independent discoveries of a comet that are reported to the CBAT
after the issuance of the announcement IAUC are usually not
considered in the naming process, unless:
- it can be shown unambiguously that the discovery claim
in question was made before any outside knowledge could
have been available to the claimant; and
- that the comet has not yet been named; and
- there are not already more than two names to be given
to the comet in question.
- The time of comet discovery is taken to be the time of the first
detection visually or the time that the image was taken upon which
the discovery was made.
- Regarding discoverers.
- Comets are to be named for their individual discoverer(s) if at all
possible. This means using the last (family) name of the
- Sometimes, however, team names are more appropriate.
- A discoverer is defined here as the person(s)
who first detect(s) the comet (visually, or on a photograph
or electronic image). He or she is responsible for obtaining
and communicating to the CBAT (possibly via a responsible
third party) accurate information on the comet's positions
and physical appearance.
- Although past comets have borne the names of three (and, on rare
occasions, more) discoverers, it is preferable to keep the limit
to two names if at all possible; more than three names are to
be avoided except in rare cases where named lost comets are
identified with a rediscovery that has already received a new
- When there are two (or more) independent discoveries of a comet,
- the discoverers' (or their teams') names are to be listed
in the chronological order in which each discoverer
(or team) found the comet,
- each individual name is to be separated by a hyphen
(but family surnames with two or more words separated
by either spaces or hyphens are to be distinguished
in comet names by single spaces only between each surname
word -- although, for simplicity, the discoverer shall
in such cases also be given the option to choose one
main word from his or her name to represent the surname
on the comet, with such choosing strongly encouraged),
- there is to be no more than one name on that comet
from a single observing location or program (excepting
the possibility of lost comets being rediscovered,
as noted in Guideline 5, below).
- Observers and observing programs (or their representatives)
cannot require the IAU to use any specific name. The final
naming process is the sole discretion of the CBAT and the CSBN
in accordance with these guidelines. For observing programs
consisting of more than two people, the established
team/program name will generally be used for the comet name
unless Guideline 3.4(a)(2), below, is satisfied.
- Occasionally a very bright comet (usually near the sun) suddenly
becomes visible to many observers worldwide nearly simultaneously
as a naked-eye object. In some of these situations, comets do not
receive the name(s) of any discoverer(s) but rather a "generic" name
such as "Great Comet" or "Eclipse Comet".
[Examples: C/1997 J2 (Meunier-Dupouy), 57P/du Toit-Neujmin-Delporte,
76P/West-Kohoutek-Ikemura, 105P/Singer Brewster,
C/1882 R1 (Great September Comet),
C/1910 A1 (Great January Comet),
C/1947 V1 (Southern Comet),
C/1948 V1 (Eclipse Comet)]
- Regarding teams of discoverers.
- Nowadays, there are very frequently teams of professional, and even
amateur, astronomers (as opposed to individuals) who find comets in
the course of their observing. It is required and presumed that
full and truthful details concerning discovery circumstances from
teams of discoverers will be given in the initial discovery report.
- Since most discoveries involve teamwork (in the broad sense that
confirmation and necessary orbit work is generally done by people not
even at the same location as the discoverer), a team is here more
narrowly defined as a group of astronomers who are formally organized
with certain instrumentation to seek and find celestial objects
- If an acceptable one-word team name (including an acronym for a
longer team name that is acceptable to the CSBN) is submitted for the
observing program, this name can be used for the comet.
- If there is no team name, either the comet shall be named for the
person who actually found the comet or the comet may receive no
name at all.
- Individual names of team members.
- In no case shall a comet contain the name of more than
two people from the same observing program. If there is
no other independent discovery, it is acceptable to have
the names of two people from the same program on a comet,
if and only if:
- there are only two team members,
- both were directly involved in the discovery (that
is, involved in making the discovery observation
and/or first identifying the comet's image), and
- their last (family) names are not identical.
- If a team (with more than two members) supplies
satisfactory written testimony that a single team
observer did the work to find the comet and note its
cometary activity, measure its position and magnitude
(or monitor an automatic computer program that does so),
and report this information, then it is acceptable for
a comet so discovered by a team program to have that
single individual's name on the comet instead of the
- The same name is not to be used twice on the same
comet, even if two discoverers share the same last name.
- Comets that are discovered from data or images made public
through printed publication or electronic posting (e.g.,
World Wide Web) are not eligible for individual names of
people and generally will not be named unless there is
an established program name for the origin of the images.
Such discoverers are considered members of the "team".
[Examples: C/1977 V1 (Tsuchinshan), C/1997 B3 (SOHO),
C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley),
P/2000 C1 (Hergenrother), P/2000 Y3 (Scotti),
C/1992 U1 (Shoemaker)]
- Regarding cometary nature that is not immediately noticed.
- It frequently happens that a comet is found by (a) discoverer(s)
--- whether a single individual, two individuals working together,
or a team --- who cannot detect cometary activity with the equipment
that he/she/they possess. Such an object may therefore be assumed
to be a minor planet and so designated when two or more nights'
worth of observations are available to the Minor Planet Center (or
posted, for example -- prior to being designated -- on the MPC's NEO
Confirmation webpage, if unusual motion is detected).
- If an observer (whether an individual or a team) who is not the
original discoverer of the "minor planet" finds that an "asteroidal"
object has a cometary appearance, and if such cometary appearance is
confirmed, both the original discoverer of the "minor planet" and the
identifier of the cometary nature may be credited in the name of the
comet, subject to the following prerequisites:
- This dual recognition in the name will occur only when
there has been no prior suspicion of the unusual nature of the
object; if the object was listed on the "NEO Confirmation Page"
or had an unusual orbit published prior to identification of
cometary appearance, the identifier of the cometary nature will
not be eligible for inclusion in the name.
- If no prior suspicion of unusual nature is suspected, the
name of the newly recognized comet can consist of two parts:
one part derived from the name of the original discoverer of the
"minor planet", and the other part derived from the name of the
discoverer of the cometary nature. EACH PART of the name
would, however, be subject to the following conditions:
- Only one name (either individual or team) is
permitted. If the "minor planet" was credited jointly
to two individuals, only one of these names can be used.
- If the original discoverer of the "minor planet" is a
team, the team cannot suggest that an individual
team-member's name be used.
- If follow-up observations performed by (an) observer(s) other
than the original discoverer of a reportedly "asteroidal" object show
the object to be a comet (that is, showing a coma and/or tail),
-- and the provisos of 4.2 do not apply -- the comet may
receive a single name of the original discoverer (individual or team).
- If the minor-planet designation was published before the realization
is made that the object is a comet, the comet will retain the
minor-planet designation. Otherwise, a new comet designation will
- If the object receives a permanent minor-planet number prior to its
recognition as a comet, it shall be accorded "dual status". As such,
it both retains the permanent minor-planet number and receives a new
- If the numbered "minor planet" has already received a name, the
comet should inherit this name.
- If the "minor planet" has not yet received a name, a new name for
the comet will be assigned according to these guidelines. The same
new name will also be used for the "minor-planet" numbering, noting
that minor-planet names must be unique.
[Examples: P/1997 B1 (Kobayashi),
P/1999 DN3 (Korlevic-Juric),
C/2000 WM1 (LINEAR);
95P = (2060) Chiron,
107P = (4015) Wilson-Harrington,
133P = (7968) Elst-Pizarro;
P/2001 BB50 (LINEAR-NEAT)]
- Regarding changes in comet names.
- The CBAT/CSBN has the option occasionally, in the interest
of fairness and/or simplicity, to change the name of a rediscovered
lost comet or in other complicated cases involving comet names (such
as names found later to be spelled incorrectly or be missing
diacritical marks, etc.). However, such changes will be made only
- Numerous one- or multi-apparition short-period comets remain lost
due to highly uncertain orbital elements (from poor sets of
observations). Sometimes such "lost" comets are rediscovered, and
occasionally the identification of the past apparition(s) is not made
until after a new name is assigned; though efforts are made to search
for identifications before naming of a new comet is made, this is
not always immediately possible, in practice.
- Comet names are generally announced on IAU Circulars by the
CBAT at the time of publication of a first set of orbital elements.
The hope is to maintain stability by preventing previously observed
comets (particularly lost comets) from getting new names.
- Occasionally this is not possible, and when a lost comet has
been given a new name(s) before it is shown to be the same comet,
the new name(s) is (are) to be added to the original name(s).
- New comets later identified with observations of "asteroidal"
objects (or previously unidentified cometary images) in previous
months or years do not get names added due to such findings after
the initial comet name is published.
- Prior to the publication of a name for a new comet, if the comet
can be identified with an object reported as asteroidal at the same
apparition on two or more nights by a single or team discoverer,
so that a minor-planet designation has already been given, it can
also have a name for that individual or team discoverer added,
provided that there is only one other name for the comet (for a
total of two names).
- Also in the stated interest of simplicity, comet names will not
be changed by adding numerals after names (where multiple comets
carry the same discoverers' names), as was done during much
of the twentieth century, as this merely complicates matters.
Officially, there is no need to retain numerals on short-period
comets that have routinely carried them in the past, because the
robust designation system obviates their necessity and because
the historical facts belie any logic associated with using numerals
(different numerals were used in different places, and there are
gaps in the numerals used even recently).
[Examples: C/1955 N1 (Bakharev-Macfarlane-Krienke),
C/1980 O1 (Cernis-Petrauskas),
C/1997 L1 (Zhu-Balam),
2P/Encke, 27P/Crommelin, 97P/Metcalf-Brewington,
- Regarding unnamed comets.
- The CSBN and CBAT reserve the right to delay naming, possibly
indefinitely. Reasons for such delay may include:
- A comet is found months or years after observation and
is no longer observable. Exceptions have been made in
connection with team names for sungrazing comets observed by
- A comet's orbit is not determinable due to poor observations
or short arc of observation; in such cases, an object will
usually be given an "X/" designation.
- There is no agreement among team members for (an) observing
program(s) claiming the discovery.
[Examples: C/1931 AN, C/1996 R3, C/1997 K2,
P/1997 T3 (Lagerkvist-Carsenty),
C/2001 HT50 (LINEAR-NEAT)]
These guidelines were discussed at length and over an extended period by
the CSBN and approved in March 2003. The prior guidelines have been moved
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I'm Tired and I Wanna Go Back to:
IAU Division III
IAU Commission 15
Department of Astronomy
M. F. A'Hearn
The Real World
Created: 2003/04/01, mfa;
Last Update: Thursday, 12-Jun-2003 18:39:51 EDT