Comet Crommelin, also known as Comet Pons-Coggia-Winnecke-Forbes, is a periodic

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

with an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of almost 28 years. It fits the classical definition of a Halley-type comet with (20 years <

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

< 200 years). It is named after the

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

Andrew C. D. Crommelin who calculated its orbit in 1930. It is one of only four comets not named after their discoverer(s), the other three being Comets

Halley Halley may refer to: Science * Halley's Comet, officially designated 1P/Halley, a comet that becomes visible from Earth every 75-76 years * Halley (lunar crater), a lunar crater named after Edmond Halley * Halley (Martian crater), a Martian cra ...

Encke Encke may refer to: *Johann Franz Encke (1791–1865), a nineteenth-century German astronomer **Encke (crater), a lunar crater **Encke Division, a dark gap in the rings of Saturn **Comet Encke, a short-period comet ***Encke (horse) (2009–2014), ...

, and Lexell. It next comes to

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

(closest approach to the Sun) in late May/early June 2039. The first observation was by

Jean-Louis Pons Jean-Louis Pons (24 December 176114 October 1831) was a French astronomer. Despite humble beginnings and being self-taught, he went on to become the greatest visual comet discoverer of all time: between 1801 and 1827 Pons discovered thirty-seven ...

(

Marseille Marseille ( , , ; also spelled in English as Marseilles; oc, Marselha ) is the prefecture of the French department of Bouches-du-Rhône and capital of the Provence-Alpes-Côte d'Azur region. Situated in the camargue region of southern Franc ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

) on February 23, 1818, he followed the comet until February 27 but was prevented further by bad weather.

Johann Franz Encke Johann Franz Encke (; 23 September 179126 August 1865) was a German astronomer. Among his activities, he worked on the calculation of the periods of comets and asteroids, measured the distance from the Earth to the Sun, and made observations ...

attempted to calculate the orbit but was left with very large errors. In 1872, John R. Hind produced a rough orbital calculation and observed it was close to that of

Comet Biela Biela's Comet or Comet Biela (official designation: 3D/Biela) was a periodic Jupiter-family comet first recorded in 1772 by Montaigne and Messier and finally identified as periodic in 1826 by Wilhelm von Biela. It was subsequently observed to ...

, based on these observations,

Edmund Weiss Edmund Weiss (26 August 1837 – 21 June 1917) was an Austrian astronomer. He was born in Frývaldov, Austrian Silesia, now Jeseník, Czech Silesia. His father, Josef Weiss (1795–1847), was a pioneer of hydrotherapy. His twin brother, Adolf Gu ...

later speculated it may have been part of Biela's comet. The next observation was on November 10, 1873, by Jérôme E. Coggia (

), and again on November 11 by Friedrich A. T. Winnecke (

Strasbourg Strasbourg (, , ; german: Straßburg ; gsw, label=Bas Rhin Alsatian, Strossburi , gsw, label=Haut Rhin Alsatian, Strossburig ) is the prefecture and largest city of the Grand Est region of eastern France and the official seat of the Eu ...

), but it was lost by November 16. Weiss and Hind took up the calculations and tried to match it again with the 1818 appearance. A third discovery was by Alexander F. I. Forbes (

Cape Town Cape Town ( af, Kaapstad; , xh, iKapa) is one of South Africa's three capital cities, serving as the seat of the Parliament of South Africa. It is the legislative capital of the country, the oldest city in the country, and the second largest ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

) on November 19, 1928, and confirmed by Harry E. Wood (

Union Observatory Union Observatory also known as Johannesburg Observatory ( 078) is a defunct astronomical observatory in Johannesburg, South Africa that was operated between 1903 and 1971. It is located on Observatory Ridge, the city's highest point at 1,808 met ...

) on November 21. It was Crommelin who eventually established the orbit and finally linked the 1818 (Pons) and 1873 (Coggia-Winnecke) comets to it ''(also see

Lost comet A lost comet is one which was not detected during its most recent perihelion passage. This generally happens when data is insufficient to reliably calculate the comet's location or if the solar elongation is unfavorable near perihelion passage. T ...

)''. On its latest return, 27P/Crommelin was recovered on May 12, 2011, at

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

18.7 and peaked at magnitude 10.7 at perihelion on August 3.

References

External links

Orbital simulation
from JPL (Java)
Horizons Ephemeris

27P/Crommelin
at the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

's Database
27P at Kronk's Cometography

Lightcurve
* 27P as seen by 10
GRAS-04
o
2011-05-30
(60 sec x 8) * 27P as seen by 20" RCOS o
2011-07-10
(30 sec x 12; Joseph Brimacombe) Periodic comets Halley-type comets 0027 027P Comets in 2011 18180223 {{comet-stub