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C/2007 N3 (Lulin)

Orbit by Kazuo Kinoshita

Image of comet LULIN on 2009 February 6
Copyright © 2009 by R. Ligustri (Talmassons, Italy)

R. Ligustri obtained this image on 2009 February 6, using an 11-cm refractor and an STL11000 CCD camera at a remote-controlled telescope in New Mexico (USA). This is a composite image using separate 60-second exposures with G and R filters, a 120-second exposure with a B filter, and a 180-second exposure with an L filter.

Discovery

This object was initially described as an asteroidal object, when found by Quanzhi Ye (Sun Yat-sen University, Guangzhou, China) on three images obtained by Chi-Sheng Lin (Institute of Astronomy, National Central University, Jung-Li, Taiwan) on 2007 July 11. Lin had acquired the images using the 41-cm Ritchey-Chretien and a CCD camera at Lulin Observatory (Nantou, Taiwan). The magnitude was given as 18.9. Several confirming observations were obtained; however, on July 17, J. Young (Table Mountain Observatory, California, USA) noted a coma 2-3" across, with a bright central core.

Historical Highlights

  • Using 76 positions spanning the period of 2007 July 11 to 17, B. G. Marsden calculated a parabolic orbit with a perihelion date of 2009 January 7.35. Even more interesting was the perihelion distance of 1.19 AU. Marsden revised his calculations a couple of days later. Using 89 positions spanning the period of July 11 to 19, he determined the perihelion date as January 14.95 and the perihelion distance as 1.24 AU.
  • The comet will pass 0.41 AU from Earth on 2009 February 24.
  • The comet steadily brightened during the last months of 2008. It was near magnitude 11.0 at the beginning of July, 10.5 at the beginning of August, 10.0 at the beginning of September, and 9.5 at the beginning of October. As the comet approached evening twilight, it was observed by a few observers at low altitude. Chris Wyatt (Australia) saw the comet with his 25-cm reflector on October 18. He gave the magnitude as 8.1 and said the moderately condensed coma was 12' across. J. J. Gonzalez (Spain) saw the comet on October 18 and 19, using 25x100 binoculars, when its altitude was only 7-8 degrees. He gave the magnitude as 8.3 on the last date, while the moderately condensed coma was 4' across. Con Stoitsis (Australia) saw the comet with his 20-cm Dobsonian on October 20. He gave the magnitude as 9.0 and said the moderately condensed coma was 4.5' across. D. A. J. Seargent (Australia) saw the comet for the final time before solar conjunction on October 27. Using 25x100 binoculars, he gave the magnitude as 8.1 and the coma diameter as 5'.
  • Following solar conjunction, the comet was picked up in the morning sky by Gonzalez on December 21. Astronomical twilight was just beginning, while the comet was 7 degrees above the horizon. His 25x100 binoculars revealed a magnitude of 7.6, while the moderately condensed coma was 2.5' across. Based on this observation, the comet's maximum magnitude in late February might reach magnitude 4.
  • The comet rapidly approached Earth and developed the typical tail pointing away from the sun, as well as an "anti-tail" pointing directly toward the sun. This unusual configuration is fairly rare and only happens when Earth passes through the orbital plane of a rather bright comet. In the case of comet Lulin, Earth stays close to the comet's orbital plane almost throughout this apparition, because the comet's orbit is inclined only slightly to the ecliptic plane (the sun-Earth plane of our solar system). Initially, these tails were only visible through photography, but some observers began reporting the anti-tail as visible through a telescope shortly after mid-February.
  • On the morning of February 21, observers were estimating the comet's brightness as between magnitude 4.5 and 5.8. The reason for the large magnitude variation stems from the large size of the comet's coma as it nears Earth. Visual observers are indicating coma diameters ranging from 15 to 25 arc minutes. For comparison, the moon is about 30 arc minutes across. The coma contains a very strong condensation. Photographers noted a new feature on the morning of February 22, as a large mass was visible northwest of the coma, apparently indicating a sudden, probably explosive emission from the coma. It will be interesting to see if this emission is an indicator of anything unusual during the next few days.
  • The comet passed closest to Earth on February 24, with the separation distance being 0.41 AU (38 million miles or 61 million kilometers).
  • Latest News:The comet is now moving away from Earth. Since it passed closest to the sun in January, the combination of increasing distances from both the sun and Earth is now causing the comet to fade. Moonlight has seriously affected observations since March 5. On March 4, observers were estimating the comet's brightness as 5.5-6.0. The coma was still 10-15 arc minutes across.
  • Additional Images

    Image of comet Lulin on 2007 July 11


    Image of comet Lulin on 2007 July 15


    Image of comet Lulin on 2008 August 19


    Image of comet Lulin on 2008 August 19


    Image of comet Lulin on 2008 August 31
    Copyright © 2008 by Gary W. Kronk (Kronk Observatory, St. Jacob, Illinois, USA)

    G. W. Kronk obtained this image on 2008 August 31, using a 20-cm Meade SCT and a MallinCam Hyper in 15-second integration mode. The best frames from a 7-minute AVI were stacked to show the comet and its motion.


    Image of comet Lulin on 2008 September 2


    Image of comet Lulin on 2009 January 23
    Copyright © 2009 by R. Ligustri (Talmassons, Italy)

    R. Ligustri obtained this image on 2009 January 23, using a 35-cm reflector and an ST10XMe CCD camera. This is a composite image using separate 60-second exposures with the B, V, and R filters, and a 180-second exposure with the L filter.


    Image of comet Lulin on 2009 January 28
    Copyright © 2009 by NASA/Swift/Univ. of Leicester/DSS (STScI, AURUA)/Bodewits et al.

    This image of Comet Lulin taken on January 28 merges data acquired by Swift's Ultraviolet/Optical Telescope (blue and green) and X-Ray Telescope (red). This image was created by taking the original image merging it with a Digital Sky Survey image of the star field.


    Image of comet Lulin on 2009 January 30
    Copyright © 2009 by Gary W. Kronk (Kronk Observatory, St. Jacob, Illinois, USA)

    G. W. Kronk obtained this image on 2009 January 30, using a 20-cm Meade SCT and a MallinCam Hyper in 2-second integration mode, with increased contrast to bring out the tail and antitail to the left and right, respectively. The best frames from two 2-minute AVIs were stacked to show the comet and its motion.


    Image of comet Lulin on 2009 January 31
    Copyright © 2009 by Gary W. Kronk (Kronk Observatory, St. Jacob, Illinois, USA)

    G. W. Kronk obtained this image on 2009 January 31, using a 20-cm Meade SCT and a MallinCam Hyper in 2-second integration mode. The best frames from a 12-minute AVI was stacked to show the comet and its motion.


    Image of comet Lulin on 2009 February 4
    Copyright © 2009 by Gary W. Kronk (Kronk Observatory, St. Jacob, Illinois, USA)

    G. W. Kronk obtained this image on 2009 February 4, using a 20-cm Meade SCT and a MallinCam Hyper in 7-second integration mode. The best frames from a 5-minute AVI was stacked to show the comet, its motion, and its tail.


    Image of comet Lulin on 2009 February 6
    Copyright © 2009 by Gary W. Kronk (Kronk Observatory, St. Jacob, Illinois, USA)

    G. W. Kronk obtained this image on 2009 February 6, using a 20-cm Meade SCT and a MallinCam Hyper in 7-second integration mode. The best frames from two 5-minute AVIs was stacked to show the comet, its motion, and the tail.


    Image of comet Lulin on 2009 February 19
    Copyright © 2009 by R. Ligustri (Talmassons, Italy)


    Image of comet Lulin on 2009 February 20
    Copyright © 2009 by Martin P. Mobberley (England)


    Image of comet Lulin on 2009 February 20
    Copyright © 2009 by J. C. McConnell (Maghaberry, Northern Ireland) and G. W. Kronk (St. Jacob, Illinois, USA)

    This is a composite of two images obtained exactly seven hours apart on 2009 February 20. At 2:33 UT, John C. McConnell (Northern Ireland) obtained a picture of the comet using a Canon 400D DSLR and a 50mm lens. At 9:33 UT, Gary W. Kronk (Illinois, USA) obtained a picture of the comet with a Canon XTi DSLR and a 100mm lens. The exposure times were 48 seconds for McConnell and 30 seconds for Kronk, with both cameras tracking the stars. The width of this image is just about 6 degrees, indicating the comet moved roughly 1.5 degrees during this time, which is about three times the width of the full moon.


    Image of comet LULIN on 2009 February 22
    Copyright © 2009 by Gary W. Kronk (Kronk Observatory, St. Jacob, Illinois, USA)

    G. W. Kronk obtained this image on 2009 February 22, using a 20-cm Meade SCT and a MallinCam Hyper in 7-second integration mode. This shows the debris cloud that has been emitted from the comet in the same general direction as the main tail.


    Image of comet Lulin on 2009 February 24
    Copyright © 2009 by Martin P. Mobberley (England)


    Image of comet Lulin on 2009 February 24
    Copyright © 2009 by Mark A. Brown (Washington DC, USA)

    M. A. Brown obtained this image on 2009 February 24, using an 8-cm Meade reflector and a Canon Digital Rebel. He obtained 26 images ranging in exposure time from 30 to 60 seconds and stacked them in Registax. Brown was fighting "brutal cold temps and wind gusts over 20mph," not to mention the light pollution from Washington DC!


    Image of comet Lulin on 2009 February 28
    Copyright © 2009 by Jan B. Timmermans (Valkenswaard, The Netherlands)


    Image of comet Lulin on 2009 February 28
    Copyright © 2009 by R. Ligustri (Talmassons, Italy)

    The comet passes the star Regulus. R. Ligustri obtained this image on February 28. He was then remotely using the R.A.S. telescope in New Mexico, USA. The telescope was a 10.6-cm refractor and the CCD camera was an SBIG STL11000.


    Image of comet Lulin on 2009 March 3
    Copyright © 2009 by Martin P. Mobberley (England)

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