C/2012 S1 (ISON) | ||
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Morning sky plots of the comet's position in December
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![]() Copyright © 2013 by Damian Peach (Selsey, West Sussex, England)
This image was acquired on 2013 November 15, using a 11-cm telescope and an STL-11k CCD camera. Several exposures using various filters were combined to make this color image, with the total exposure time amounting to 12 minutes. Latest News (Updated November 30, 2013 @ 20:49 UT)
![]() Copyright © 2013 by NASA/SOHO
This image was acquired on 2013 November 30 at about 19:42 UT by the Solar and Heliospheric Observatory (SOHO) spacecraft using the Large Angle and Spectrometric Coronagraph (LASCO) C3 camera. The remnants of the comet are near the top of the image. Discovery Vitali Nevski and Artyom Novichonok were expecting to use the International Scientific Optical Network's (ISON) 40-cm reflector at Kislovodsk Observatory (Russia) on the night of 2012 September 20/21, but clouds halted their plans...at least for most of the night. About a half hour prior to the beginning of morning twilight, they noticed the sky was clearing and got the telescope and CCD camera up and running to obtain some survey images in the Gemini and Cancer region. After twilight began, Novichonok left to get some rest, while Nevski loaded the images into a program called CoLiTec, which is designed to detect asteroids and comets moving between images. Nevski noted a rather bright object with unusually slow movement, which he thought could only mean it was situated beyond the orbit of Jupiter. The images showing the object were all acquired during the period of September 21.05-21.07. Notice of the discovery was sent to the Central Bureau for Astronomical Telegrams, which immediately placed the object on the NEOCP web page of the Minor Planet Center, so that other observers could obtain confirming images. It was then uncertain whether the object was a minor planet or a comet. Novichonok booked time on the 1.5-m reflector at Majdanak Observatory (Uzbekistan) and O. Burhonov answered the call by acquiring images on September 21.99. Although these new images revealed Nevski and Novichonok had discovered a comet, other observers following up on the NEOCP web site had already reported the cometary appearance, so the comet was named ISON, instead of being named after the discoverers. ![]() Copyright © 2012 by A. Novichonok (ISON-Kislovodsk Observatory, Russia)
This is an image of the discoverers of comet ISON. Artyom Novichonok is on the left and Vitali Nevski is on the right.
![]() Copyright © 2012 by V. Nevski and A. Novichonok (ISON-Kislovodsk Observatory, Russia)
This is very first image that was acquired by Nevski and Novichonok on 2012 September 21.05. The comet is in the middle of the circle.
Prediscovery images were found by G. V. Williams (in the survey archives of the Mount Lemon Survey (Arizona, USA) and Pan-STARRS 1 (Haleakala, Hawaii, USA). The three Mount Lemon images were obtained using the 1.5-m reflector and a CCD camera during 2011 December 28.35-28.38 and revealed a magnitude range of 19.5-19.9. The three Pan-STARRS 1 images were obtained using the 1.8-m refelctor and a CCD camera during 2012 January 28.45-28.50 and indicated a magnitude range of 19.8-20.6.
Early Orbit Calculations While on the NEOCP web page, the object was designated AS03D20. Maik Meyer (Germany) took an interest in this object and began calculating orbits. He published his first orbit on the "comets-ml" group on Yahoo on 2012 September 23 at 10:29 UT. This used 33 positions spanning September 21-23, giving the perihelion date as 2013 October 19.62 and the perihelion distance as 0.03 AU. The latter number was enough for Meyer to include the text "Something to dream of?" At 15:59 UT, Meyer sent a revised orbit to "comets-ml" which used 40 positions from September 21-23. The perihelion date was given as 2013 November 14.97, while the perihelion distance was 0.01 AU. He commented, "still looks good. There is a q=2.x solution but with T in 2010, so I still would bet a few Euro's on the low-q solution." Meyer's final orbit came nearly 24 hours later, when he announced on the "comets-ml" group that 50 positions spanning September 21-24 indicated a perihelion date of 2013 November 1.03 and a perihelion distance of 0.02 AU. Later that same day, at 18:40 UT, the Minor Planet Center sent a notice which provided all available observations of this comet, including the prediscovery images received from Mount Lemon and Pan-STARRS 1. The resulting orbit used 54 positions spanning 2011 December 28 to 2012 September 23, giving the perihelion date as 2013 November 28.87 and the perihelion distance as 0.012 AU. We now know that the comet passed perihelion on November 28.78 at a distance of 0.012 AU. The comet seems to be fresh from the Oort cloud, meaning that this is likely the first time it has approached the Sun since the birth of our solar system.
Speculation
*Several people have suggested the comet might reach a maximum magnitude of -6 to -10 when the comet is closest to the sun, which would enable it to be seen in broad daylight. As of 2012 September 25, the Central Bureau for Astronomical Telegrams web site indicated a maximum brightness of -13.1 on 2013 November 28 at 21:00 UT.
Will the comet hold together?
Observations
Additional Images ![]() Copyright © 2011 by E. Guido, G. Sostero, and N. Howes (Michelago, New South Wales, Australia)
This image was acquired on 2012 September 22.5 (UT), while remotely using a 25-cm reflector and CCD camera at the RAS Observatory near Mayhill, New Mexico, USA. It is a stack of twenty-four 120-second exposures. This reveals a slightly diffuse object with a coma 5 arc seconds across.
![]() Copyright © 2012 by Michael Jäger (Austria)
This image was acquired on 2012 September 24, using a 25-cm reflector and an FLI 8300 CCD camera. Four 7.5-minute exposures were combined to make this image.
![]() Copyright © 2013 by R. Ligustri (Italy)
This image was acquired on 2013 January 16, using the remote 45-cm reflector and an FLI PL6303E CCD camera at Mayhill, New Mexico. The comet is indicated by the tick marks to the right of the middle of the image. [This is a crop of the original image]
![]() Copyright © 2013 by NASA/JPL-Caltech/JHUAPL/UCF
These images from NASA's Spitzer Space Telescope of C/2012 S1 (Comet ISON) were taken on June 13, when ISON was 310 million miles (about 500 million kilometers) from the sun. The images were taken with the telescope's infrared array camera at two different near-infrared wavelengths, 3.6 and 4.5 microns (the representational colors shown were selected to enhance visibility). The 3.6-micron image on the left shows a tail of fine rocky dust issuing from the comet and blown back by the pressure of sunlight as the comet speeds towards the sun (the tail points away from the sun). The image on the right side shows the 4.5-micron image with the 3.6-micron image information (dust) removed, and reveals a very different round structure -- the first detection of a neutral gas atmosphere surrounding ISON. In this case, it is most likely created by carbon dioxide that is "fizzing" from the surface of the comet at a rate of about 2.2 million pounds (1 million kilograms) a day. According to the Spitzer web site, the observations revealed "what most likely are strong carbon dioxide emissions." At a distance of 312 million miles (502 million kilometers) from Earth, the indicated tail length was 186,400 miles (300,000 kilometers) long.
![]() Copyright © 2013 by Rolando Ligustri (Italy)
This image was acquired on 2013 September 25, using the remote 45-cm reflector and an FLI PL6303E CCD camera at Mayhill, New Mexico. This was a 25-minute exposure.[This is a crop of the original image]
![]() Copyright © 2013 by Rolando Ligustri (Italy)
This images was acquired by Ligustri on 2013 September 28. The image reveals Mars in the lower right quadrant, comet ISON in the upper right quadrant, and the asteroid 433 Eros on the left side of the image.
![]() Copyright © 2013 by NASA/JPL/University of Arizona
These images were acquired by the Mars Reconnaissance Orbiter on 2013 September 29, when comet ISON was located about 8 million miles from the planet Mars.
![]() Copyright © 2013 by Martin P. Mobberley (England)
![]() Copyright © 2013 by Michael Jäger (Austria)
This image was acquired on 2013 October 5, using a 20-cm reflector and an ASA SXV-H9 CCD camera. Several exposures using various filters were combined to make this color image, with the total exposure time amounting to 63 minutes.
![]() Copyright © 2013 by Adam Block (Mount Lemmon SkyCenter, University of Arizona, USA)
This image was acquired on 2013 October 8, using an 81-cm reflector and an SBIG STX16803 CCD camera. Several exposures using various filters were combined to make this color image, with the total exposure time amounting to 52 minutes.
![]() Copyright © 2013 by Martin P. Mobberly (England)
![]() Copyright © 2013 by Michael Jäger (Austria)
This image was acquired on 2013 October 31, using a 20-cm reflector and an FLI 8300 CCD camera. Several exposures using various filters were combined to make this color image, with the total exposure time amounting to 20 minutes.
![]() Copyright © 2013 by Martin P. Mobberly (England)
![]() Copyright © 2013 by Denis Buczynski (Tarbatness Observatory, Portmahomack, Scotland)
![]() Copyright © 2013 by Martin P. Mobberly (England)
![]() Copyright © 2013 by Damian Peach (Selsey, West Sussex, England)
This image was acquired on 2013 November 6, using a 43-cm reflector and an FLI-PL6303e CCD camera. Several exposures using various filters were combined to make this color image, with the total exposure time amounting to 19 minutes.
![]() Copyright © 2013 by Adam Block (Mount Lemmon SkyCenter, University of Arizona, USA)
This image was acquired on 2013 November 8, using an 81-cm reflector and an SBIG STX16803 CCD camera. Several exposures using various filters were combined to make this color image, with the total exposure time amounting to 36 minutes.
![]() Copyright © 2013 by Damian Peach (Selsey, West Sussex, England)
This image was acquired on 2013 November 10, using a 11-cm telescope and an STL-11k CCD camera. Several exposures using various filters were combined to make this color image, with the total exposure time amounting to 18 minutes.
![]() Copyright © 2013 by Erik Bryssinck (BRIXIIS Observatory, Belgium)
This image was acquired on 2013 November 15, using a 0.4-m astrograph and a CCD camera. The exposure time was 3 minutes.
![]() Copyright © 2013 by NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute
This image was acquired on 2013 November 20 by the Messenger spacecraft (in orbit around the planet Mercury) using the Wide Angle Camera of the Mercury Dual Imaging System. The comet was then at its closest distance from Mercury, which was about 22.5 million miles (36.2 million kilometers).
![]() Copyright © 2013 by José J. Chambó (La Llosa de Ranes, Valencia, Spain)
This image was acquired on 2013 November 20, using a 20-cm reflector and a Canon EOS 350D camera. Fifteen 25-second exposures at ISO 800 were combined to create this image.
![]() Copyright © 2013 by Gerald Rhemann (Austria)
This image was acquired on 2013 November 21 while Rhemann was visiting Namibia in Africa. It was acquired usng an ASA 31-cm astrograph and an FLI ML 8300 CCD camera. Four total exposures were combined to produce this color image: a 3-minute exposure with an L filter and separate 2-minute exposures with R, G, and B filters. Rhemann said the skies were excellent, which accounts for the excellent photo despite the fact that the first exposure was obtained when the comet was only about 1.5 degrees above the horizon, while the last was made when the comet was at an altitude of only 5 degrees.
![]() Copyright © 2013 by Michael Jäger (Austria)
This image was acquired on 2013 November 22 at 5:00 UT, using a 8-cm APO refractor and an Kai 11002 CCD camera, as well as an 18-cm APO refractor and a KAF 6300 CCD camera. Several exposures using various filters were combined to make this color image, with the total exposure time amounting to nearly 10 minutes.
![]() Copyright © 2013 by NASA/STEREO
This image was acquired on 2013 November 22 at 5:29 UT by the STEREO Ahead spacecraft using the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) hi1 camera. The image shows the present locations of the planets Mercury and Earth, as well as two comets. Comet ISON is the brightest, with bright tail extending toward the left. Comet Encke is a periodic comet that returns every 3.3 years and is displaying a very faint tail toward the left.
![]() Copyright © 2013 by NASA/STEREO
This image was acquired on 2013 November 23 at 5:29 UT by the STEREO Ahead spacecraft using the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) hi1 camera. The image shows the present locations of the planets Mercury and Earth, as well as two comets. Comet ISON is the brightest, with bright tail extending toward the left. Comet Encke is a periodic comet that returns every 3.3 years and is displaying a very faint tail toward the left.
![]() Copyright © 2013 by Pete Lawrence (Roques de los Muchachos Observatory, La Palma, Canary Islands)
This image was acquired on 2013 November 23 at about 6:30 UT, using the 254-cm Isaac Newton Telescope and a Canon 40D camera. This is a 30-second exposure at ISO 400.
![]() Copyright © 2013 by NASA/STEREO
This image was acquired on 2013 November 24 at 5:29 UT by the STEREO Ahead spacecraft using the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) hi1 camera. The image shows the present locations of the planets Mercury and Earth, as well as two comets. Comet ISON is the brightest, with bright tail extending toward the left. Comet Encke is a periodic comet that returns every 3.3 years and is displaying a very faint tail toward the left.
![]() Copyright © 2013 by NASA/STEREO
This image was acquired on 2013 November 25 at 5:29 UT by the STEREO Ahead spacecraft using the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) hi1 camera. The image shows the present locations of the planets Mercury and Earth, as well as two comets. Comet ISON is the brightest, with bright tail extending toward the left. Comet Encke is a periodic comet that returns every 3.3 years and is displaying a very faint tail toward the left.
![]() Copyright © 2013 by NASA/SOHO
This image was acquired on 2013 November 27 at 13:30 UT by the Solar and Heliospheric Observatory (SOHO) spacecraft using the Large Angle and Spectrometric Coronagraph (LASCO) C3 camera. The image shows comet ISON toward the far right.
![]() Copyright © 2013 by NASA/SOHO
This image was acquired on 2013 November 28 at 0:54 UT by the Solar and Heliospheric Observatory (SOHO) spacecraft using the Large Angle and Spectrometric Coronagraph (LASCO) C3 camera.
![]() Copyright © 2013 by NASA/SOHO
This image was acquired on 2013 November 28 at 21:48 UT by the Solar and Heliospheric Observatory (SOHO) spacecraft using the Large Angle and Spectrometric Coronagraph (LASCO) C2 camera. |
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