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http://www.asyura.com/2003/bd24/msg/643.html
投稿者　日時 2003 年 2 月 28 日 19:34:46:

(回答先: Re: ついにやってくるぞ、ニート彗星！投稿者 RT 日時 2003 年 2 月 28 日 18:31:54)

http://www.cometography.com/lcomets/2002v1.html

G A R Y ﾊ W. ﾊ K R O N K ' S ﾊ C O M E T O G R A P H Y

Comet C/2002 V1
NEAT

Orbit and Ephemeris by Central Bureau for Astronomical Telegrams

Analysis by Seiichi Yoshida

This image was obtained by Rolando Ligustri and Lucio Furlanetto using a 350/1750 Newtonian reflector and an ST9E CCD camera on 2003 January 29.73. It is a combination of six images exposed to reveal the complexity of the tail.

Discovery

S. H. Pravdo (Jet Propulsion Laboratory) announced that the 1.2-m Schmidt telescope at Haleakala had found a comet on 2002 November 6.60 in the course of the Near Earth Asteroid Tracking (NEAT) program. It exhibited a tail extending 10 arcsec toward PA 225｡. With additional images on November 6.61 and November 6.62, the magnitude was estimated as between 17.1 and 17.5. The comet was confirmed by M. Blasco and S. Sanchez (Mallorca) on November 6.83 using the 0.40-m Schmidt telescope. They noted the coma was 15 arcsec across.

Historical Highlights
* The first orbit was published by Brian G. Marsden of the Central Bureau for Astronomical Telegrams on 2002 November 7 (MPEC 2002-V31 and IAUC 8011). Using 39 positions from November 6 and 7, he calculated a parabolic orbit with a perihelion date of 2003 February 18.59 and a perihelion distance of 0.0999 AU. Marsden confirmed the general correctness of the orbit on November 8 (MPEC 2002-V41) when 54 positions from November 6 to 8 revealed a perihelion date of 2003 Feb. 17.72 and a perihelion distance of 0.0987 AU. After more positions became available, the perihelion date was firmly established as February 18.30, the perihelion distance was given as 0.0993 AU, and the orbital period was about 37 thousand years. The orbit indicates the comet passed closest to Earth on December 24 (0.80 AU) and will be situated 5.7｡ from the sun around the time of perihelion.

* Total magnitude estimates of this comet have been somewhat discordant during December, with the size of the telescope being a major factor. As the month began, most visual magnitude estimates were within the range of 12 to 12.5. The comet brightened to between 11 and 11.5 by December 8 and was between 10 and 10.5 by the 14th. Moonlight blocked the comet from view between December 15 and 21. Numerous observers began switching to large binoculars after December 22, at which time magnitude estimates became more consistent. The total visual magnitude was between 9.0 and 9.5 around the 24th and between 8.0 and 8.5 around the 29th.

* Using observations obtained by the German comet section up to December 26, Andreas Kammerer analyzed the brightness trend of this comet and has stated that the rapid increase in brightness "is typical of a small nucleus." Although he said the trend indicates a possible maximum brightness of magnitude -15 at the time of perihelion in February, he predicted the following on December 27: "During the first period (which I expect will end during the next two weeks) the brightness increases rapidly. Thereafter the increase will noticably slow down and come to an end, followed by a rapid decline due to the disintegration of the nucleus." On December 23, John Bortle had wrote, "No comet as intrinsically faint as 2002V1 is presently thought to be has survived through a perihelion distance of 0.1 AU." In other words, it seems unlikely that this comet will survive long enough to become an impressive daylight object in February.

* Observations during the first half of January were mostly affected by moonlight, with the moon passing just 12｡ from the comet on the 9th. On January 1 and 2, most observers reported magnitudes ranging from 7.6 to 8.6 and coma diameter estimates ranging from 6 to 12 arcmin. On the 14th and 15th, most observers reported magnitudes ranging from 6.8 to 7.5 and coma diameter estimates ranging from 5 to 12 arcmin. Occasional reports of a tail were received throughout this period. Taking the magnitude estimates of experienced observers, the comet appears to have continued to rapidly brightening throughout this period. The publication of a new orbit on January 15, indicates the comet is moving in a long-period orbit with a period of about 37 thousand years. This indicates this small comet has survived passages through perihelion in the past, and makes a breakup seem a little less likely.

* Several interesting announcements were made during the second half of January. Pepe Manteca (Spain) obtained CCD images on the 17th which revealed an apparent tail disconnection event. The first naked-eye observation was reported by Michael J拡er (Austria) on January 20. He then gave the magnitude as 6.3. J拡er obtained a photograph that same evening which revealed a gas tail extending 2.5｡. On the 23rd, an analysis by Seiichi Yoshida (Japan) indicated the comet had slowed in its rate of brightening, with the change having occurred around January 9.

* The comet's changed rate of brightening appeared to slow again beginning around February 3, as observers were reporting brightness estimates below the predicted values. Observers were then generally giving the magnitude as 5, while the degree of condensation was between 7 and 8. Visual estimates of the tail length were generally between 1｡ and 2｡, with extreme estimates near 6｡. As the comet's angular distance from the sun continued to decrease, many observers began losing the comet in evening twilight, but observations resumed for many observers on February 7 and 8 with the report of an outburst in brightness. Although magnitude estimates are very difficult to make when comets are in strong twilight, many observers were indicated the outburst amounted to 0.5 to 1 magnitude, which place the brightness between 4 and 4.5. Further magnitude estimates placed the comet at 3.5 on the 10th, 3.0 on the 12th, and about 2.0 very late on the 13th.

* The comet entered the field of view of the Solar & Heliospheric Observatory (SOHO) on February 16.

This image is a collage of four images obtained by the Solar & Heliospheric Observatory (SOHO) at 10:54 UT on 2003 February 17, 18, 19, and 20. The white circle near the center of the left margin represents the outline of the sun.

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Additional Images
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This photograph was obtained by Michael J拡er on 2002 December 1.80. It is a 9.5-minute exposure obtained with a 200/300 Schmidt camera and Kodak TP2415 hypered film.

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This image was obtained by G. Sostero on 2002 December 10.99. The image is composed of 10 120-second exposures obtained with a 0.3m f/2.8 Baker-Schmidt camera and a CCD camera..

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This image was obtained by Pepe Manteca on 2003 January 17. There is a knot of material located two-thirds of the way down the tail from the coma, which may be a tail disconnection event. It is best seen in this animation. Additional images and movies of this comet can be found at Manteca's web site.

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This photograph was obtained by Michael J拡er on 2003 January 20.72. It is a combination of two 7-minute exposures obtained with a 200/300 Schmidt camera and Kodak TP hypered film.

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This photograph was obtained by Michael J拡er using a 200/300 Schmidt camera on 2003 January 28.74. It is a combination of two 6-minute exposures obtained with Kodak Ektachrome 100S and one 7-minute exposure obtained with Kodak TP.

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This image was obtained by high school students at Amtsgymnasiet and EUC Syd (Sonderborg, Denmark) on 2003 January 31.73. The students were Soren V. Andersen, David Lange, Martin Sorensen, Kristian Mandrup, and Michael Jensen. It is a composite of 43 50-second exposures obtained with a telescope and a CCD camera. Other images of the comet obtained by this class are located on their webpage

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This photograph was obtained by Michael J拡er using a 250/450 Schmidt camera on 2003 February 9.74. It is a combination of two 1-minute exposures obtained with Kodak Ektachrome 100S and two 5-minute exposures obtained with Kodak TP.

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This image was obtained by Ginger Mayfield (Colorado) on 2003 February 10. It is an unguided 8-second exposure obtained with a Canon D60 digital SLR on a tripod. The outside temperature was then -3｡ F.

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