C / 1972 E1 (Bradfield)

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C / 1972 E1 (Bradfield) [i]
Properties of the orbit ( animation )
Epoch:  March 24, 1972 ( JD 2,441,400.5)
Orbit type long-period
Numerical eccentricity 0.9981
Perihelion 0.927 AU
Aphelion 989 AE
Major semi-axis 495 AU
Sidereal period ~ 11,000 a
Inclination of the orbit plane 123.7 °
Perihelion March 27, 1972
Orbital velocity in the perihelion 43.7 km / s
history
Explorer WA Bradfield
Date of discovery March 12, 1972
Older name 1972 III, 1972f
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1972 E1 (Bradfield) is a comet that in 1972 could only be observed with optical aids.

Discovery and observation

The comet was discovered by William A. Bradfield in Australia on the morning of March 13, 1972 (local time) . He had since the beginning of 1971 already a total of 260 hours with a mm 150 - f / 5.5 - Refractor for comets sought. It was his first comet discovery of many to come. Bradfield estimated the comet's brightness to be 10 mag and was able to observe its new discovery on the following days, but transmission problems lost its repeated sighting reports and it was not until March 22 that its discovery was confirmed by other observers in Australia.

The comet reached its greatest brightness of about 8 mag during April, making it the brightest comet of the year. Zenón M. Pereyra was able to take a long-term recording in Córdoba (Argentina) , which showed a tail almost 1 ° long. The comet reached its greatest southern declination in mid-April and then quickly faded. By mid-May the brightness had already fallen back to 10 mag. The last observation was made on June 7th in South Africa .

Orbit

Brian Marsden was able to determine a limited precise elliptical orbit for the comet from 70 observation data over a period of 72 days , which is inclined by around 124 ° to the ecliptic . It thus runs in the opposite direction (retrograde) like the planets through its orbit. At the point of the orbit closest to the sun ( perihelion ), which the comet last traversed on March 27, 1972, it was only slightly closer to the sun than the earth , at about 138.7 million km from the sun . On April 26th, it came close to Earth to about 0.83  AU / 124.9 million km. On May 4th the comet approached Venus up to about 118.1 million km and on August 5th the comet passed Mars at a distance of about 105.4 million km.

The comet moves in an extremely elongated elliptical orbit around the sun. According to the orbital elements afflicted with a certain uncertainty, its orbit some time before the passage of the inner solar system in 1972 had an eccentricity of about 0.9979 and a semi-major axis of about 435 AU, so that its orbital period was about 9100 years. Although the comet had a few relatively close passages of Saturn on October 6, 1970 and November 7, 1974 in slightly more than 7 AU, and at Jupiter on March 16, 1972 in about 4 ¾ AU, the orbital eccentricity was due to the forces of attraction of the Planets not changed significantly. The semi-major axis was only slightly enlarged to about 444 AU, so that its orbital period increased to about 9400 years.

See also

Individual evidence

  1. ^ Astronomical Society of South Australia: Comets Discovered from South Australia. Accessed December 12, 2015 .
  2. ^ BG Marsden: Comets in 1972. In: Quarterly Journal of the Royal Astronomical Society. Vol. 14, 1973, pp. 389-406 ( bibcode : 1973QJRAS..14..389M ).
  3. ^ Gary W. Kronk , Maik Meyer : Cometography - A Catalog of Comets, Volume 5, 1960-1982. Cambridge University Press, Cambridge 2010, ISBN 978-0-521-87226-3 , pp. 325-327.
  4. ↑ NASA JPL Small-Body Database Browser: C / 1972 E1 (Bradfield). Retrieved December 11, 2015 .
  5. ↑ A. Vitagliano: SOLEX 11.0. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .
  6. ^ E. Everhart, BG Marsden: New original and future cometary orbits. In: The Astronomical Journal. Vol. 88, 1983, pp. 135-137 doi: 10.1086 / 113298 ( bibcode : 1983AJ ..... 88..135E ).