|
|
Discovery
This comet was discovered by Jean Louis Pons (Florence, Italy) and Adolphe Gambart (Marseilles, France) on 1827 June 21. Although no system was in place to estimate comet brightnesses at that time, various astronomers have since suggested the comet was then between magnitude 5 and 6.
Historical Highlights
Few physical descriptions were published for this comet. Pons was the most prolific observer, measuring three additional positions in June and a total of 17 in July. The comet attained its most northerly declination of +83° on June 26. J. E. B. Valz (Nîmes, France) saw the comet on the morning of July 5 and 6, and on the evening of July 6, with a nearly full moon in the sky. The comet attained its maximum observed elongation of 63° on July 7. The comet was last detected on July 21 by Pons. He said the comet was extremely faint. Pons added that the comet could not be observed thereafter because of its faintness and the fact that it had entered a region of the sky containing numerous nebulosities.
A month of observations did not generate great interest in examining the orbit of this comet. It was not until 1828 that the first parabolic orbits appeared in the Astronomische Nachrichten. During March, Valz took positions spanning the entire period of visibility and determined the perihelion date as 1827 June 8.83. One month later, A. de Heiligenstein essentially used the same positions and determined a perihelion date of June 8.37.
There was no further interest until the 20th century, when, during 1917, S. Ogura took 74 positions spanning the period of visibility, and found the orbit was distinctly elliptical. His best orbit had a perihelion date of June 7.69 and a period of 63.83 years, with a likely uncertainty in the period of +/-10 years. A second orbit with a period of 46.0 years was calculated, but it did not fit the positions as well.
S. Nakano reinvestigated the orbit in 1978. He said the 1827 observations were best represented by an orbit with a perihelion date of June 7.64 and a period of 57.46 years, but suggested a probable error of +/-10 years. The comet was considered hopelessly lost.
In 1979, I. Hasegawa introduced an interesting twist to the investigation of this orbit. He pointed out that S. Kanda had noted in 1972 that there was a "probable" link between comet Pons-Gambart and a comet seen in 1110. Hasegawa began examining the observations published in ancient Chinese and Korean texts and was able to derive three rough positions, with which he then calculated a parabolic orbit. He confirmed the resemblance to comet Pons-Gambart.
A comet was found by Rob Matson (Newport Coast, California, USA) on images obtained during 2012 November 7 to 19 by the SWAN instrument aboard the SOHO spacecraft. Terry Lovejoy (Thornlands, Queensland, Australia) obtained confirming images on November 29 and 30 and Rob H. McNaught (Siding Spring Observatory, New South Wales, Australia) obtatined several images on November 30 using the 51-cm Uppsala Southern Schmidt telescope. Maik Meyer (Limburg, Germany) and G. V. Williams (Minor Planet Center, Massachusetts, USA) independently suggested this was Pons-Gambart. Although it was referred to as the "lost" comet, it turned out that the orbits published in the past were considerably off on the period and this was actually the comet's first return since its discovery in 1827.
|
|
