21P/Giacobini-Zinner

Japanese version
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Updated on March 1, 2014

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* Profile

The light curve is stable, though the brightening and fading is rather rapid along a 18.5 log r formula.

Kazuo Kinoshita's calculation revealed that it passes close by Earth and Jupiter frequently in 20th and 21st century. But the orbit does not change so much. So the light curve will be similar in any appearance.

However, comparing the light curves in 1998 and 2005, there are some slight differences. The light curve was symmetric to the perihelion passage in 2005, but it became brightest about two weeks before the perihelion passage in 1998. The maximum brightness was similar in both appearances, but it was brighter in 1998 before or after the perihelion passage.

* Returns and Appearances

!Discovered *Appeared -Not observed #Appeared before discovery +Not observed before discovery .Returns in the future
.
2018 Sept. 10
* 21P
2012 Feb. 11
* 21P
2005 July 2
* 21P
1998 Nov. 21
* 21P
1992 Apr. 13
* 21P
1985 Sept. 5
* 21P
1979 Feb. 12
* 21P
1972 Aug. 4
* 21P
1966 Mar. 28
* 21P
1959 Oct. 26
-
1953 Apr. 16
* 21P
1946 Sept.18
* 21P
1940 Feb. 17
* 21P
1933 July 15
* 21P
1926 Dec. 11
-
1920 May 18
* 21P/1913 U1
1913 Nov. 2
-
1907 May 19
! 21P/1900 Y1
1900 Nov. 28

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The perihelion dates in the past appearances are printed on Catalog of Cometary Orbits 1996.
The perihelion dates of non-observed returns from 1907 to 1953 are calculated using the Minor Planet & Comet Ephemeris Service.
Information on the discovery and historical highlights are available at General Comet Info (Gary W. Kronk).
The past and future orbital elements calculated by Kazuo Kinoshita (http://www9.ocn.ne.jp/~comet/pcmtn/0021p.htm).

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Copyright(C) Seiichi Yoshida (comet@aerith.net). All rights reserved.