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C/2006 M4 (SWAN)

Orbit by Kazuo Kinoshita

Image of comet SWAN on 2006 September 30
Copyright © 2006 by Michael Jäger and Gerald Rhemann (Austria)

Michael Jäger and Gerald Rhemann obtained this image of comet SWAN on 2006 September 30.13. This was obtained with a 25-cm Schmidt Camera, with an ASA Corrector and a Sigma 1603 CCD camera.

Discovery

R. D. Matson (Irvine, California, USA) and M. Mattiazzo (Adelaide, South Australia, Australia) independently reported a possible comet shortly before early July of 2006. The comet was found on images obtained using the SWAN camera aboard the Solar and Heliospheric Observatory (SOHO) spacecraft during the period of June 20 to July 5. A request for confirmation revealed a couple of immediate responses. First, T. Lovejoy (Thornlands, Queensland, Australia) found a 12-magnitude image taken on June 30 using a digital camera. He said the coma was about 0.5 arc minutes across and exhibited a greenish hue. Second, R. H. McNaught (Siding Spring Observatory, Australia) photographed the comet on July 12, using the 0.5-m Uppsala Schmidt reflector. He determined the magnitude as 12.3 and said the comet was strongly condensed, with a short tail.

Historical Highlights

  • A preliminary parabolic orbit was published on IAU Circular 8729 (2006 July 12) by D. W. E. Green. It indicated a perihelion date of 2006 August 24.2 and a perihelion distance of 0.132 AU. A revision was published by Green's colleague, B. G. Marsden, on July 15. Marsden took 15 positions spanning the period of July 12-15 and determined the perihelion date as 2006 September 28.92. This proved very close to the true orbit, as shown by later calculations by Marsden on July 21, July 28, and August 4. Marsden published an orbit on September 21 which revealed that the comet moved in a hyperbolic orbit.
  • Following an observation by D. A. J. Seargent (Cowra, New South Wales, Australia) on July 20, the comet became lost in twilight. The comet moved through the field of the SOHO C3 camera during the period spanning August 12 to 30 and through the field of the narrower SOHO C2 camera during the period spanning August 19 to 23. The comet was finally recovered in the morning sky on September 19. J. J. Gonzalez (Leon, Spain) spotted it on September 19.19 using 25x100 binoculars when the comet was only 7 degrees above the horizon. K. Yoshimoto (Yamaguchi, Japan) obtained an image of the comet on September 19.83 using a 15-cm reflector and a CCD camera.
  • Widespread observations began near the end of September. The comet's altitude has stayed fairly low up to early October, which is making it a difficult object for most people. It is true that some observers have reported the comet visible to the naked eye, but the conditions must be exceptional for this to happen. The Author has found the comet quite easy to see with binoculars during the first days of October and has found it simply by sweeping the region between the handle of the Big Dipper and the tail of Leo. Its appearance is that of a small, round, fuzzy ball of light.
  • The comet became an easy evening sky object shortly before mid-October and experienced a very noticeable outburst in brightness on the night of October 23/24. The comet's visual magnitude increased to at least 4.5, which made it an easy naked-eye object for observers with dark skies, which included the Author. On October 25, I found the coma to be about 15 arc minutes across in 20x80 binoculars.
  • Additional Images

    Image of comet SWAN on 2006 September 24
    Copyright © 2006 by Michael Jäger and Gerald Rhemann (Austria)

    Michael Jäger and Gerald Rhemann obtained this image of comet SWAN on 2006 September 24. This is a 3-minute 15-second exposure obtained with an ASA 20-cm Astrograph and a Sigma 3200 CCD camera.


    Image of comet SWAN on 2006 October 8
    Copyright © 2006 by G. Sostero & E. Guido (Mt. Ioanaz, Italy)


    Image of comet SWAN on 2006 October 15
    Copyright © 2006 by Gary W. Kronk (Illinois, USA)

    G. W. Kronk obtained this image of comet SWAN on 2006 October 15. Two one-minute long movies were obtained using a Meade 20-cm Schmidt-Cassegrain GPS and a MallinCam Hyper video camera. Each movie was stacked using Registax and the images were then stacked using Registax.


    Image of comet SWAN on 2006 October 21
    Copyright © 2006 by Gary W. Kronk (Illinois, USA)

    G. W. Kronk obtained this image of comet SWAN on 2006 October 21. Eight 30-second long movies were obtained using a Meade 20-cm Schmidt-Cassegrain GPS and a MallinCam Hyper video camera. Each movie was stacked using Registax and the images were then stacked and averaged using Astrometrica.


    Image of comet SWAN on 2006 October 24
    Copyright © 2006 by Gary W. Kronk (Illinois, USA)

    G. W. Kronk obtained this image of comet SWAN on 2006 October 24.02. Nine 30-second long movies were obtained using a Meade 20-cm Schmidt-Cassegrain GPS and a MallinCam Hyper video camera. Each movie was stacked using Registax and the images were then stacked and averaged using Astrometrica. The comet was then experiencing an outburst in brightness.


    Image of comet SWAN on 2006 October 25
    Copyright © 2006 by Gary W. Kronk (Illinois, USA)

    G. W. Kronk obtained this image of comet SWAN on 2006 October 25.02. Five 30-second long movies were obtained using a Meade 20-cm Schmidt-Cassegrain GPS and a MallinCam Hyper video camera. Each movie was stacked using Registax and the images were then stacked and averaged using Astrometrica. The comet was then experiencing an outburst in brightness.


    Image of comet SWAN on 2006 October 30
    Copyright © 2006 by Mark Brown (Florida, USA)

    M. Brown obtained this image of comet SWAN on 2006 October 30.0. It is a composite of twenty-two images obtained during a period of 50 minutes. He used a Canon Digital Rebel attached to a 20-cm Celestron SCT.


    Image of comet SWAN on 2006 October 30
    Copyright © 2006 by Gary W. Kronk (Illinois, USA)

    G. W. Kronk obtained this image of comet SWAN on 2006 October 30.02. Two 40-second long movies were obtained using a Meade 20-cm Schmidt-Cassegrain GPS and a MallinCam Hyper video camera. Each movie was stacked using Registax and the images were then stacked and added using Astrometrica. Some work was done in PhotoShop to bring out the tail a little more.

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