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C/2009 P1 (Garradd)

Orbit by Kazuo Kinoshita

Image of comet Garradd on 2011 September 2
Copyright © 2011 by Rolando Ligustri (Italy)

R. Ligustri obtained this image of the comet on 2011 September 2. He was remotely using the GRAS 11-cm refractor and a STL8300C CCD camera located in New Mexico (USA). This was a single 300-second exposure as the comet approached the "Coat Hanger" asterism in Vulpecula.

Discovery

G. J. Garradd (Siding Spring Observatory, Australia) discovered this comet on four images obtained between 2009 August 13.77 and August 13.81. He was using the 0.5-m Uppsala Schmidt telescope and a CCD camera. The magnitude was given as 17.5-17.7 and the coma was described as circular and 15" across. The first confirmation was obtained by W. Robledo (El Condor Observatory, Cordoba) on August 14.17.

Historical Highlights

  • The first parabolic orbit was calculated by B. G. Marsden on 2009 August 15. He took 10 positions from the period spanning 2009 August 13-15 and determined the perihelion date as 2011 August 10.23. The perihelion distance was given as 1.25 AU, indicating the comet could become a fairly bright object. It was obvious that the comet was located far from the sun, possibly near 8 AU, which would make it difficult to quickly pin down the orbit. A revision was published by Marsden on August 19. Using 14 positions from the period of August 13-18, he determined the perihelion date as 2012 February 4.83. Another revision was published by Marsden on August 23. This used 18 positions from the period of August 13 to 23 and determined the perihelion date as 2012 January 8.43. The orbit was eventually established as being hyperbolic with a perihelion date of 2011 December 23.67.
  • Numerous observatories followed the comet during the remainder of 2009 and basically revealed the comet maintained a brightness of 17-18. It was lost in the sun's glare shortly after 2010 began and the comet passed 28 degrees from the sun on February 26. As the solar elongation increased, the comet was next observed on 2010 May 9, at which time the magnitude had brightened to 16.3. Shortly thereafter, on May 14, the comet's northerly motion stopped when it attained a declination of -31.7 degrees and it turned southward...making it an increasingly difficult object for observers in the Northern Hemisphere. Further observations by CCD cameras revealed the comet slowly brightened to magnitude 15 by mid-August.
  • The first visual observation came on August 20, when J. J. Gonzalez (Leon, Spain) located the comet using his 20-cm reflector. He gave the magnitude as 12.8 and noted a moderately condensed coma 0.7' across. The comet was then nearing its greatest solar elongation of 150 degrees, which it reached on August 28. Chris Wyatt (Walcha, New South Wales, Australia) visually picked up the comet on three occasions during September. His 25-cm reflector revealed a magnitude range of 13.7 to 14.5, while the coma diameter was 1-1.5 arc minutes across. After having moved southward since mid-May, the comet attained a declination of -38.3 degrees on September 17 and then turned northward. During the remainder of the year, the comet continued to brighten, although some observers began struggling near year's end as the comet drew closer to the sun. Nevertheless, it appeared to be brighter than magnitude 11 during the final days of December.
  • The comet was becoming increasingly difficult to observe as 2011 began, as the comet's elongation from the sun was rapidly decreasing. The only possible visual observation made during January came from Alexandre Amorim (Florianopolis, Brazil) on the 3rd, when he suspected seeing the comet in his 18-cm reflector when it was 21 degrees above the horizon. He estimated the magnitude as 10.5 and said the coma was 1' across. Several observers did acquire definite observations using CCD cameras through the 16th. The comet passed 10 degrees from the sun on February 19.
  • After being lost in the sun's glare for nearly three months, the comet was recovered on April 3 by Wyatt, using his 25-cm reflector. The comet's altitude was then only 15 degrees above the horizon. He described the comet as diffuse and slightly elongated toward the north. The total magnitude was given as 12.7. A few hours earlier, Amorim had tried to observe the comet using this 18-cm reflector, but was unsuccessful, estimating that the comet was still fainter than magnitude 11.0. On April 4, A. Novichonok and D. Chestnov remotely imaged the comet using an 18-cm reflector and a CCD camera at Tzec Maun Observatory (Moorook, South Australia, Australia). They gave the total magnitude as 11.7 and the nuclear magnitude as 13.3. The coma was 1.1' across. Novichonok and Chestnov acquired a follow-up observation using a 15-cm refractor at Tzec Maun Observatory on the 6th. They noted a magnitude of 11.9 and a coma diameter of 1.5'.
  • Since the comet's April recovery, observations have steadily increased. The comet brightened to magnitude 10 by the end of May, 9 by the end of June, and was near 8 by the end of July. The coma also increased in diameter during this period, with observers using binoculars noting it was 8-10' across, by the end of July.
  • The comet was at a maximum solar elongation of 149 degrees on August 8, which meant the comet was pretty much visible throughout the night. Observations were made from all over the world, with the comet brightening from about magnitude 8 to about magnitude 7 during the month. The diameter of the coma generally remained 8-10' across throughout the month. Images acquired by a large number of observers continually revealed a tail extending toward the southeast.
  • After having moved northward since September 2010, the comet will attained a declination of +19.9 degrees on 2011 September 12 and then turned southward.
  • The southward motion continued until 2011 October 26, when the comet attained a declination of +18.7 degrees and then resumed a northward motion.
  • The comet reached a minimum solar elongation of 45 degrees on 2011 December 5.
  • Upcoming Highlights

  • The comet will be closest to Earth on 2012 March 5 (1.27 AU).
  • The comet will attain its most northerly declination of +70.7 degrees on 2012 March 11 and will move steadily southward for the remainder of the year.
  • The comet will reach a maximum solar elongation of 112 degrees on 2012 March 17.
  • The comet will reach a minimum solar elongation of 4 degrees on 2012 August 16.
  • Additional Images

    Image of comet Garradd on 2009 August 15
    Copyright © 2009 by E. Guido, P. Camilleri, G. Sostero, and E. Prosperi (Italy)

    E. Guido, P. Camilleri, G. Sostero, and E. Prosperi obtained this image on 2009 August 15, using the remote 35-cm reflector and a CCD camera located in Grove Creek Observatory (Trunkey Creek, New South Wales, Australia). They co-added twenty 60-second exposures.


    Image of comet Garradd on 2011 April 6
    Copyright © 2011 by A. Novichonok and D. Chestnov (Italy)

    A. Novichonok and D. Chestnov obtained this image on 2011 April 6, using the remote 15-cm refractor and a CCD camera located in Tzec Maun Observatory (Moorook, South Australia, Australia).


    Image of comet Garradd on 2011 July 5
    Copyright © 2011 by Josef Mueller (Germany)

    J. Mueller obtained this image of the comet on 2011 July 5.05. He was using a 15-cm refractor and an ST10-XME CCD camera. This image is the result of combining four 300-second exposures. The total magnitude was given as 10, while the coma was 3.5' across. Tails were extending 6' in PA 175 degrees and 6' in PA 239 degrees.

    Image of comet Garradd on 2011 July 8
    Copyright © 2011 by Rolando Ligustri (Italy)

    R. Ligustri obtained this image of the comet on 2011 July 8.21. He was remotely using the GRAS 51-cm reflector and a FLI 11002 CCD camera located in New Mexico (USA).


    Image of comet Garradd on 2011 July 26
    Copyright © 2011 by Francois Kugel (Observatoire Chante-Perdix, Dauban, Haute-Provence, France)

    F. Kugel and C. Rinner obtained this image of the comet on 2011 July 26.05. They was using a 50-cm reflector and a CCD camera. The magnitude of the nucleus shining from within the coma is 11.1.


    Image of comet Garradd on 2011 August 26
    Copyright © 2011 by Michael Jager (Austria)

    M. Jager acquired this image of the comet on 2011 August 26. He was using a 25-cm reflector and an FLI8300 CCD camera. The picture was assembled using images obtained with RGB filters that were each 240-second exposures.


    Image of comet Garradd on 2011 September 4
    Copyright © 2011 by Gary W. Kronk (Illinois, USA)

    G. W. Kronk acquired this image of the comet on 2011 September 4. He was using an 8-cm reflector and a modified Canon T2i camera with a green filter. Four 3-minute exposures were stacked to produce this image.


    Image of comet Garradd on 2012 January 31
    Copyright © 2012 by Gerald Rhemann (Eichgraben, Austria)

    G. Rhemann acquired this image of the comet on 2012 January 31. He was using a 30-cm astrograph and an FLI8300 CCD camera. The picture was assembled using a 30-minute exposure with an L filter, a 15-minute exposure with an R filter, a 15-minute exposure with a G filter, and a 20-minute exposure with a B filter.The comet's bluish gas tail nearly passes over the galaxy NGC 6339.


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