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Copyright © 2007 by Gary W. Kronk (Kronk Observatory, Illinois, USA)
G. W. Kronk obtained this image on 2007 July 21. He was using a Meade 20-cm Schmidt-Cassegrain reflector and a MallinCam Hyper video camera. Ultimately, 1647 frames from a six-minute AVI were stacked in Registax.
Discovery
This object was discovered on 2006 November 13.13, by the Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) project in New Mexico, which used a 1.0-m reflector and a CCD camera. The magnitude was given as 19.9. Other LINEAR images obtained between November 13.15 and 13.18 indicated a magnitude of 19.8-20.4. The object appeared stellar on all images. The orbit released on November 16 indicated it was an Amor minor planet with a period of over 40 years. On November 28, R. Miles (Golden Hill Observatory, Stourton Caundle, Dorset, England, UK) photographed the comet using a 28-cm Schmidt-Cassegrain and a CCD camera and noted the object appeared slightly softer than stellar images.
Historical Highlights
A very preliminary parabolic orbit was published by the Central Bureau on 2006 November 16. Still believing this was a minor planet, T. B. Spahr made an assumption about the eccentricity and then took 35 positions spanning the period of 2006 November 13 to 16, and determined a perihelion date of 2007 September 20 and a period of 40.5 years. Following the recognition that this was a comet, B. G. Marsden calculated a parabolic orbit on December 4, which gave the perihelion date as 2007 August 11. The orbit proved to be hyperbolic with a perihelion date of August 10.89.
The comet attained a solar elongation of about 30 degrees around mid-March of 2007. On the 12th, M. Reszelski (Poland) spotted the comet at magnitude 16.0 and noted a coma 0.5' across.
The comet seemed to be brighter than predicted during April. M. L. Paradowski (Lublin, Poland) spotted the comet at an altitude of 19.7 degrees on April 21 using his 20-cm reflector. He gave the magnitude as 12.0 and said the coma was 2.2' across. An observation by Paradowski on April 22, revealed a similar appearance, except the magnitude was 11.7. Also on the 22nd, M. Jager photographed the comet and said it was not brighter than magnitude 13.5. He noted a "small condensed coma with faint outer halo 1-1.5' [across]." On April 28, S. Yoshida (Gunma, Japan) observed the comet using a 40-cm reflector. He gave the magnitude as 13.3 and noted the coma was 0.6' across.
The comet seemed to maintain a brightness between magnitude 13 and 14 during May. A. Hale (New Mexico, USA) suspected the comet on May 12. C. Labordena (Castellon, Spain) saw the comet using a 24-cm Schmidt-Cassegrain reflector on the 13th. He gave the magnitude as 13.2 and the coma diameter as 1'. Hale saw the comet under much better conditions on May 14. He gave the magnitude as 13.5 and noted a coma 0.7' across.
The comet was brighter than magnitude 12 as June began. On the 4th, J. J. Gonzalez (Leon, Spain) was observing with his 20-cm reflector from a mountain location. He gave the magnitude as 11.7 and the coma diameter as 2.0'. Another observation by Gonzalez on the 5th indicated a magnitude of 11.1 and a coma 2.5' across. On the 7th, W. Kutschera (Feldatal, Germany) observed using a 54-cm reflector and gave the magnitude as 11.4. He noted the coma was 2.0' across. On June 8, the magnitude was given as 11.1 by W. Hasubick (Buchloe, Germany) and 11.4 by Kutschera. The coma diameter was given as 1.3' by Hasubick and 2.4' by Kutschera. On June 12, P. Creed (Grantsville, West Virginia, USA) observed using a 10-cm refractor and gave the magnitude as 10.0, while Gonzalez observed using 25x100 binoculars and gave the magnitude as 10.3. They both gave the coma diameter as 3'. On June 14, Paradowski estimated the magnitude as 11.0 in haze. He said the coma was 2.5' across. There were numerous observers during the second half of June. They indicated that the comet steadily brightened to slightly brighter than magnitude 9 by month's end, while the coma was then around 5' across.
July began with the comet at about magnitude 8.5, while the coma was around 6' across. As the days passed, more and more observers began detecting the comet using binoculars, which revealed a larger coma and brighter magnitude. On the 6th, T. Scarmato (Calabria, Italy) observed with 7x50 binoculars. He gave the magnitude as 7.5 and the coma diameter as 14'. Most observers were reporting a magnitude around 7.5 by mid-July. Photographically, hints of a tail had been detected in June, but visual observers did not report a tail until July 12, when C. S. Morris (Fillmore, California, USA) estimated the length as 5' using 20x80 binoculars. On the 13th, Kutschera reported a tail 14' long in his 25-cm reflector. The comet passed 0.57 AU from Earth on 2007 July 14.
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