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141P/Machholz 2

Past, Present, and Future Orbits by Kazuo Kinoshita

M. Jäger image of 141P exposed on 1994 September 8
Copyright © 1994 by Michael Jäger (Austria)

The photograph was taken on 1994 September 8.09 UT, using an 8-inch Schmidt camera. It shows four of the nuclei seen during that apparition. Besides the bright comet with a tail, there is a small, faint comet above and to the left that is almost touching the coma of the bigger one. The other two comets are near the upper left corner.


     This comet was discovered by Donald E. Machholz (Colfax, California, USA) on 1994 August 13.42 with a 0.25-m reflector. He estimated the brightness as magnitude 10 and said the coma diameter was 3 to 4 arc minutes across. Machholz added that the comet was diffuse with little condensation. The comet was confirmed in twilight by T. Kojima (YGCO Chiyoda Observatory, Japan) on April 13.80. He said the comet was diffuse with condensation.

Historical Highlights

  • The first orbit was determined by S. Nakano (Sumoto, Japan) and was published on 1994 August 15. It was parabolic and indicated a perihelion date of 1994 September 13.76, a perihelion date of 0.757 AU, and an inclination of 15 degrees. The first elliptical orbit was computed by Daniel W. E. Green of the Central Bureau for Astronomical Telegrams and was published on August 23. He found a perihelion date of 1994 September 17.82, a perihelion distance of 0.753 AU, and an orbital period of 6.81 years. By late September, further observations generally confirmed this early short-period orbit, although the period had been revised to 5.23 years.
  • Michael Jäger (Vienna, Austria) reported his discovery of a second comet just 48 arc minutes from comet Machholz 2 on August 28.04. He said it appeared to have the same motion as Machholz 2 and estimated the magnitude as 11. This comet continued being observed during the days that followed. A third object was independently found on September 2.11 by Petr Pravec (Ondrejov Observatory) and on September 3.51 by Wayne Johnson (Anza, California, USA). It was 43 arc seconds from the second object and about 1 magnitude fainter. Fourth and fifth objects were found by Pravec on September 4.1 and confirmed elsewhere. Letter designations were assigned to the 5 comets on September 21. The primary comet was the most westward and was designated "A". Working eastward, "B" was the fourth comet found, "C" was the third comet, "D" was the second comet, and "E" was the fifth comet. Interestingly, Pravec reported that CCD images obtained on October 5.14 indicated "D" exhibited two condensations within its coma.
  • Although initial brightness estimates indicated the comet would barely exceed magnitude 10, the comet continued brightening as the various components were discovered, probably indicating increased reflectivity because of excess dust output as a result of the breakup. The main comet's maximum magnitude peaked at about 7 during the first days of September.
  • The comet was recovered by R. H. McNaught (Siding Spring Observatory, Australia) on 1999 August 3.55. The comet then appeared stellar, with the magnitude estimated as 20.3-20.8. Calculations revealed this was comet "A", as designated from 1994, with the predicted orbit requiring a correction of only +0.8 day. A search for other components failed to reveal anything.
  • The comet brightened slowly and finally came within range of the large amateur telescopes at the end of October and beginning of November, when estimates of the brightness were near 12. Interestingly, McNaught reported a single image obtained at Siding Spring on October 17 showed component D had appeared. This was confirmed by Jäger and Gerald Rhemann on October 27. Jäger and Rhemann said D was running about one magnitude fainter than A.
  • At the end of November both components A and D were near magnitude 12, with a diameter of 2 arc minutes. As December progressed, component A brightened, while D began to fade. Around mid-month component A was near magnitude 11.5, and it had brightened to around 10 by month's end. Component D remained near 12 until near mid-month at which time it dropped to 13. It was close to 13.5 as the month ended. As 1999 ended, component A was about 5 arc minutes across, while D was typically estimated as 3-4 arc minutes in diameter.
  • Additional Images

    Photo of comet Machholz 2
    Copyright © 1994 by Herman Mikuz (Crni Vrh Observatory, Slovenia)

    This image was obtained on 1994 October 11.16 using a 20-cm, f/2 Baker-Schmidt telescope, V filter and ST-6 CCD. The exposure time was 5 minutes and shows fragments A and D of this comet. The webmaster has converted the image to black and white, and cropped it to save space.

    Photo of comet Machholz 2 on 1999 November 26
    Copyright © 1999 by Michael Jäger (Austria)

    This image was obtained on 1999 November 26.73 using a 0.25-m Schmidt camera. The exposure time was 26 minutes and shows fragments A and D of this comet. Fragment A was estimated as magnitude 11.8, while D was estimated as 12.3.