Discovery of a Periodic Comet, and its Naming

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Updated on September 11, 2016

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* Overview

Discovery of a comet, that is finding a new comet nobody has ever known before for the first time in the world.

Some comets are rotating around the Sun and returns repeatedly. They are called periodic comets. It is not a discovery if you catch a returning periodic comet.

But actually, it is often impossible to predict the return of a periodic comet because the orbital elements are uncertain or it has been lost for a long time. Such a periodic comet comes to be discovered several times whenever it returns.

When was such a periodic comet discovered indeed? Here I consider the definition of "discovery" of a periodic comet based on the past cases.

I also derive and verify the naming rule of a periodic comet from this definition of "discovery".

* Analysis

o Discovery of a periodic comet

Analyzing the cases of past periodic comet discoveries, I derive the definition of "discovery" of a periodic comet as follows.

  • When a comet was discovered and its periodicity was calculated, it is recognized as "discovery" as a periodic comet.
  • Even if a comet has been discovered before, it is not recognized as "discovery" as a periodic comet if its periodicity was not calculated.
    • Ex: Record of 1P/Halley in 240 B.C. in China.
      Not called as 1P/Chinese Comet.
    • Ex: Discovery by La Hire in 1678.
      Not called as 6P/La Hire, but 6P/d'Arrest.
  • Even if the period is uncertain and it has been lost, the comet has been already "discovered" as a periodic comet. Even if it comes to be accidentally discovered later, it is not recognized as "discovery" as a periodic comet.
    • Ex: Discovery of D/de Vico in 1995.
      Not called as 122P/de Vico-Nakamura-Tanaka.
  • Even if it has been discovered as an asteroid before, it is not recognized as "discovery" as a periodic comet. When it comes to be accidentally discovered as a comet later, this is recognized as "discovery" as a periodic comet.
    • Ex: Discovery of Asteroid 1925 QD by Shajn in 1925.
      Not called as 36P/Shajn-Whipple, but 36P/Whipple.

Note that here I derive the definition to determine only one apparition recognized as "discovery" as a periodic comet among many recorded apparitions. I do not describe on the priority among discoverers in one apparition.

In this definition, "discovery" as a periodic comet does not mean the time when the object was found for the first time in the world. There can be some records of apparitions before the "discovery".

In this definition, "discovery" as a periodic comet does not coincide with the time when people actually become aware of the comet. For example, the "discovery" as a periodic comet of Comet D/1977 C1 ( Skiff-Kosai ) is in 1976 based on this definition, however, it was announced in 1986. The perihelion passage in 1984 is a return after the "discovery", but actually, nobody knew about this comet at that time.

o Naming of a periodic comet

Based on the definition of "discovery" as a periodic comet mentioned above, I derive the definition of naming of a periodic comet as follows.

  • A periodic comet is named after the discoverers recognized when it was "discovered" as a periodic comet.
  • If the object has been discovered before it was "discovered" as a periodic comet, it is named as follows.
    1. If they were identified at the same time when it was "discovered" as a periodic comet, it is named after the discoverers in both cases.
      • Ex: When P/1858 E1 ( Winnecke ) was discovered, it was identified with C/1819 L1 ( Pons ) at the same time.
        Named as 7P/Pons-Winnecke.
    2. If it was "discovered" as a periodic comet because identified with other comets, it can be named after the calculator.
      • Ex: 1P/Halley.
    3. If it was "discovered" as a periodic comet, then it was identified with other comets after that, the names of the discoverers in the latter cases are deleted, even if they have discovered the comet before "discovered" as a periodic comet.
      • Ex: 6P/d'Arrest was discovered in 1851, then it was identified with C/1678 R1 ( La Hire ).
        Not renamed as 6P/La Hire-d'Arrest, but remained as 6P/d'Arrest.
  • If it was "discovered" as a periodic comet, it became lost, and then it was accidentally rediscovered again, it is named as follows.
    1. Until 1994, the names of the rediscoverers are added.
      • Ex: Rediscovery of D/Metcalf by Brewington in 1991.
        Renamed as 97P/Metcalf-Brewington.
    2. Since 1995, the names of the rediscoverers are not added.
      • Ex: Rediscovery of D/de Vico in 1995.
        Not renamed as 122P/de Vico-Nakamura-Tanaka, but remained as 122P/de Vico.

* Consideration

Here I evaluate the definition mentioned above on the periodic comets which have been discovered several times, and verify the definition.

o 1P/Halley

All apparitions were recorded since 240 B.C. But the ancient apparitions were only recorded. The orbital elements were calculated in the Middle Ages, but they were parabolic and no periodicity was calculated.

After the apparition in 1682, Halley identified three comets, C/1531 P1, C/1607 S1, C/1682 Q1, and calculated the periodicity for the first time. Therefore it was discovered as a periodic comet at the apparition in 1682.

o 2P/Encke

It was discovered in 1786 by Mechain, in 1795 by Herschel, in 1805 by Pons, Huth, Bouvard, in 1818 by Pons respectively.

After the apparition in 1819, Encke identified these comets and calculated the periodicity for the first time. Therefore it was discovered as a periodic comet at the apparition in 1819.

o 3D/Biela

It was discovered in 1772 by Montaigne, in 1805 by Pons, in 1826 by Biela respectively.

Gauss has identified the two comets in 1772 and 1805, and calculated the periodicity already in 1806. Therefore it was discovered as a periodic comet at the apparition in 1805, discovered by Pons. The discovery in 1826 by Biela is recognized as recovery.

This definition derives the name of this comet should be 3D/Montaigne-Pons-Biela.

o 6P/d'Arrest

Comet in 1678 discovered by La Hire was identified with 6P/d'Arrest in 1990.

No periodicity was calculated for the comet in 1678. Therefore it was discovered as a periodic comet at the apparition in 1851, discovered by d'Arrest, and the name of La Hire was deleted.

o 7P/Pons-Winnecke

It was discovered in 1819 by Pons, in 1858 by Winnecke respectively. They were identified at the discovery in 1858.

No periodicity was calculated in 1819. Therefore it was discovered as a periodic comet at the apparition in 1858, discovered by Winnecke.

o 8P/Tuttle

It was discovered in 1790 by Mechain, in 1858 by Tuttle respectively. They were identified at the discovery in 1858.

No periodicity was calculated in 1790. Therefore it was discovered as a periodic comet at the apparition in 1858, discovered by Tuttle.

This definition derives the name of this comet should be 8P/Mechain-Tuttle.

o 11P/Tempel-Swift-LINEAR

It was discovered in 1869 by Tempel. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1880 by Swift is recognized as recovery.

The names of the recoverers must not be added to the comet in 2001. Therefore the name of this comet should be 11P/Tempel-Swift.

o 12P/Pons-Brooks

It was discovered in 1812 by Pons. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1883 by Brooks is recognized as recovery.

o 18D/Perrine-Mrkos

It was discovered in 1869 by Perrine. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1955 by Mrkos is recognized as recovery.

o 21P/Giacobini-Zinner

It was discovered in 1900 by Giacobini. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1913 by Zinner is recognized as recovery.

o 23P/Brorsen-Metcalf

It was discovered in 1847 by Brorsen. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1919 by Metcalf is recognized as recovery.

o 26P/Grigg-Skjellerup

It was discovered in 1902 by Grigg, in 1922 by Skjellerup respectively. They were identified at the discovery in 1922.

No periodicity was calculated in 1902. Therefore it was discovered as a periodic comet at the apparition in 1922, discovered by Skjellerup.

o 27P/Crommelin

It was discovered in 1818 by Pons, in 1873 by Coggia, Winnecke, in 1928 by Forbes, Yamasaki respectively.

No periodicity was calculated in 1818. But in 1873, the comets in 1818 and 1873 were identified and the periodicity was calculated. Therefore it was discovered as a periodic comet at the apparition in 1873, discovered by Coggia, Winnecke.

Not similar to the cases of 1P/Halley and 2P/Encke, Crommelin researched the orbit after it was discovered as a periodic comet. Therefore, this definition derives the name of this comet should be 27P/Pons-Coggia-Winnecke-Forbes-Yamasaki.

o 35P/Herschel-Rigollet

It was discovered in 1788 by Herschel, in 1939 by Rigollet respectively. They were identified at the discovery in 1939.

No periodicity was calculated in 1788. Therefore it was discovered as a periodic comet at the apparition in 1939, discovered by Rigollet.

o 36P/Whipple

Asteroid 1925 QD discovered by Shajn was identified with 36P/Whipple in 1987.

No periodicity was calculated for Asteroid 1925 QD. Therefore it was discovered as a periodic comet at the apparition in 1933, discovered by Whipple, and the name of Shajn was rejected.

o 38P/Stephan-Oterma

It was discovered in 1867 by Stephan. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1942 by Oterma is recognized as recovery.

o 41P/Tuttle-Giacobini-Kresak

It was discovered in 1858 by Tuttle, in 1907 by Giacobini, in 1951 by Kresak respectively.

The periodicity was calculated in 1858. Therefore it was discovered as a periodic comet at that time. The discoveries in 1907 by Giacobini and in 1951 by Kresak are recognized as recovery.

o 43P/Wolf-Harrington

It was discovered in 1924 by Wolf. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1951 by Harrington is recognized as recovery.

o 54P/de Vico-Swift-NEAT

It was discovered in 1844 by de Vico. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1894 by Swift is recognized as recovery.

The names of the recoverers must not be added to the comet in 2002. Therefore the name of this comet should be 54P/de Vico-Swift.

o 64P/Swift-Gehrels

It was discovered in 1889 by Swift. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1973 by Gehrels is recognized as recovery.

o 72P/Denning-Fujikawa

It was discovered in 1881 by Denning. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1978 by Fujikawa is recognized as recovery.

o 74P/Smirnova-Chernykh

Asteroid 1967 EU was identified with 74P/Smirnova-Chernykh in 1980s.

No periodicity was calculated for Asteroid 1967 EU. Therefore it was discovered as a periodic comet at the apparition in 1975, discovered by Smirnova, Chernykh, and the names of the discoverers of Asteroid 1967 EU were rejected.

o 79P/du Toit-Hartley

It was discovered in 1945 by du Toit. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1982 by Hartley is recognized as recovery.

o 80P/Peters-Hartley

It was discovered in 1846 by Peters. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1982 by Hartley is recognized as recovery.

o 97P/Metcalf-Brewington

It was discovered in 1906 by Metcalf. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time. The discovery in 1991 by Brewington is recognized as recovery.

o 104P/Kowal 2

Comet in 1973 discovered by Boethin was identified with 104P/Kowal 2 in 2003.

No periodicity was calculated for the comet in 1973. Therefore it was discovered as a periodic comet at the apparition in 1979, discovered by Kowal, and the name of Boethin was rejected.

o 107P/(4015) Wilson-Harrington

It was discovered in 1949 by Wilson, Harrington as a comet D/1949 W1. Then it was discovered in 1979 by Helin as an asteroid 1979 VA. Because the orbit of D/1949 W1 was uncertain and the comet had been lost, they were considered as different objects.

The period of Asteroid 1979 VA was concluded and it was registered as (4015). After that, Asteroid (4015) was identified with Comet D/1949 W1.

However, Cunningham has calculated the periodicity already in 1949. Therefore it was discovered as a periodic comet at that time, and the name of Helin was rejected.

o 109P/Swift-Tuttle

Comet in 1737 discovered by Kegler was identified with P/Swift-Tuttle in 1970s.

No periodicity was calculated for the comet in 1737. Therefore it was discovered as a periodic comet at the apparition in 1869, discovered by Swift, Tuttle, and the name of Kegler was deleted.

o 122P/de Vico

It was discovered in 1995 by Nakamura, Tanaka, Utsunomiya, Seki, Machholz. But it was identified with Comet D/de Vico discovered in 1846.

The periodicity was calculated in 1846. Therefore it was discovered as a periodic comet at that time, and the names of recoverers in 1995 were rejected.

o 133P/(7968) Elst-Pizarro

Asteroid 1979 OW7 was identified with 133P/Elst-Pizarro later.

No periodicity was calculated for Asteroid 1979 OW7. The period of this asteroid was concluded and it was registered as (7968) after the identification. Therefore it was discovered as a periodic comet at the apparition in 1996, discovered by Elst, Pizarro, and the names of the discoverers of Asteroid 1979 OW7 were rejected.

o 139P/Vaisala-Oterma

Asteroid 1939 TN discovered by Vaisala, Oterma was revealed to be a comet in 1981.

After that, Asteroid 1998 WG22 discovered by LINEAR was identified with 1939 TN.

The periodicity was calculated already in 1981. Therefore it was discovered as a periodic comet at the apparition in 1939, discovered by Vaisala, Oterma, and the name of LINEAR was rejected.

o 146P/Shoemaker-LINEAR

The names of the recoverers must not be added to the comet in 2000. Therefore the name of this comet should be 146P/Shoemaker.

o 148P/Anderson-LINEAR

It was discovered in 1963 by Anderson. The periodicity was calculated. Therefore it was discovered as a periodic comet at that time.

The names of the recoverers must not be added to the comet in 2000. Therefore the name of this comet should be 148P/Anderson.

o 153P/Ikeya-Zhang

Comet in 2002 discovered by Ikeya, Zhang, Raymundo was identified with Comet in 1661 observed by Hevelius.

No periodicity was calculated for the comet in 1661. Therefore it was discovered as a periodic comet at the apparition in 2002.

The comet in 1661 had no official name. But it was identified at the same time when this comet was discovered as a periodic comet. Therefore, if it had been named after Hevelius, the name of this comet would have been 153P/Hevelius-Ikeya-Zhang.

o 156P/Russell-LINEAR

It was discovered in 1986 by Russell as a comet, in 1993 by Shoemaker as Asteroid 1993 WU, in 2000 as Asteroid 2000 QD181 respectively.

The comet in 1986 was not confirmed whether real or false. Asteroid 1993 WU had been lost because the orbital elements were uncertain. Therefore these three were considered as different objects at the discovery of 2000 QD181.

In 2001, Asteroids 1993 WU and 2000 QD181 were identified. But the orbital elements were not concluded and the asteroid was not numbered at that time.

In 2003, this asteroid was identified with the comet in 1986. Then this object was discovered as a periodic comet by this identification. Therefore it was discovered as a periodic comet at the apparition in 2000, discovered by LINEAR.

No periodicity was calculated in 1986. The comet in 1986 was identified at the same time when the object was discovered as a periodic comet. Therefore the name of this comet is definitely 156P/Russell-LINEAR.

o 158P/Kowal-LINEAR

It was discovered in 1979 by Kowal as Comet C/1979 O1, in 2001 by LINEAR as Asteroid 2001 RG100 respectively.

In 2003, the asteroid in 2001 was revealed to be a comet, and it was identified with the comet in 1979.

No periodicity was calculated in 1979. Therefore it was discovered as a periodic comet at the apparition in 2001, discovered by LINEAR.

The comet in 1979 was identified at the same time when the object was discovered as a periodic comet. Therefore the name of this comet is definitely 158P/Kowal-LINEAR.

o 169P/NEAT

It was discovered in 2002 by NEAT as Asteroid 2002 EX12. It was revealed to be a comet in 2005.

It was not accidentally discovered as a new comet. Therefore it was discovered as a periodic comet at the apparition in 2001, although originally discovered as an asteroid.

o 174P/(60558) Echeclus

It was discovered in 2000 by Spacewatch as Asteroid 2000 EC98. After it was registered as Asteroid (60558), it was revealed to be a comet in 2005.

It was not accidentally discovered as a new comet. Therefore it was discovered as a periodic comet at the apparition in 2015, although originally discovered as an asteroid. However, it is in the same apparition in 2015, when it was revealed to be a comet.

o 176P/(118401) LINEAR

It was discovered in 1999 by LINEAR as Asteroid 1999 RE70. After it was registered as Asteroid (118401), it was revealed to be a comet in 2006.

It was not accidentally discovered as a new comet. Therefore it was discovered as a periodic comet at the apparition in 2000, although originally discovered as an asteroid.

o 302P/Lemmon-PanSTARRS

It was discovered in 2014 by Pan-STARRS 1 telescope as a comet. At the same time, it was identified with an asteroid 2007 RJ236 discovered by Mount Lemmon Survey in 2007, and the periodicity was calculated.

It was discovered as a periodic comet in 2014. Because it was identified at the same time when it was "discovered" as a periodic comet, it was named after the discoverers in both cases.

* Appendix

o Difference between naming by this definition and official name

No.Official NameNaming by This Definition
3DBielaMontaigne-Pons-Biela
8PTuttleMechain-Tuttle
11PTempel-Swift-LINEARTempel-Swift
27PCrommelinPons-Coggia-Winnecke-Forbes-Yamasaki
54Pde Vico-Swift-NEATde Vico-Swift
146PShoemaker-LINEARShoemaker
148PAnderson-LINEARAnderson
206PBarnard-BoattiniBarnard
226PPigott-LINEAR-KowalskiPigott
271Pvan Houten-Lemmonvan Houten
274PTombaugh-TenagraTombaugh

o Periodic comets including the recoverers' names

No.Official NameNaming Excluding the Recoverers' Names
3DBielaMontaigne-Pons
11PTempel-Swift-LINEARTempel
12PPons-BrooksPons
18DPerrine-MrkosPerrine
21PGiacobini-ZinnerGiacobini
23PBrorsen-MetcalfBrorsen
27PCrommelinPons-Coggia-Winnecke
38PStephan-OtermaStephan
41PTuttle-Giacobini-KresakTuttle
43PWolf-HarringtonWolf
54Pde Vico-Swift-NEATde Vico
64PSwift-GehrelsSwift
72PDenning-FujikawaDenning
79Pdu Toit-Hartleydu Toit
80PPeters-HartleyPeters
97PMetcalf-BrewingtonMetcalf
146PShoemaker-LINEARShoemaker
148PAnderson-LINEARAnderson
206PBarnard-BoattiniBarnard
226PPigott-LINEAR-KowalskiPigott
271Pvan Houten-Lemmonvan Houten
274PTombaugh-TenagraTombaugh

o Rediscoveries of periodic comets since 1995

DesignationNo.NameRediscoverers
P/1995 S1122Pde VicoNakamura, Utsunomiya, Tanaka, Machholz, Seki
P/1998 WG22139PVaisala-OtermaLINEAR
P/1998 X2140PBowell-SkiffWilliams, LINEAR
P/2000 ET90143PKowal-MrkosLINEAR
P/2000 S2146PShoemaker-LINEARLINEAR
P/2000 SO253148PAnderson-LINEARLINEAR
P/2001 X311PTempel-Swift-LINEARLINEAR
P/2002 T454Pde Vico-Swift-NEATNEAT
P/2003 A1226PPigott-LINEAR-KowalskiLINEAR
P/2003 T1157PTrittonJuels, Holvercem
P/2003 WY25289PBlanpainCatalina Sky Survey, Pan-STARRS
P/2006 B7198PODASWilliams
P/2006 M3177PBarnard 2LINEAR
P/2007 A1184PLovas 2Kowalski
P/2008 R6205PGiacobiniItagaki, Kaneda
P/2008 T3206PBarnard-BoattiniBoattini
P/2008 X4210PChristensenWatson
P/2009 MB9222PLINEARMcNaught
P/2009 R2226PPigott-LINEAR-KowalskiKowalski
P/2012 A3P/2003 T12SOHOWatson
P/2012 TB36271Pvan Houten-LemmonLarson
C/2012 V4273PPons-GambartMatson
P/2012 WX32274PTombaugh-TenagraSchwartz, Holvorcem
P/2012 Y2275PHermannPan-STARRS
P/2016 Q3
LINEARKowalski

* References

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