C / 1999 A1 (Tilbrook)

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C / 1999 A1 (Tilbrook) [i]
Properties of the orbit ( animation )
Epoch:  January 20, 1999 ( JD 2,451,198.5)
Orbit type long-period
Numerical eccentricity 0.9959
Perihelion 0.731 AU
Aphelion 353 AU
Major semi-axis 177 AU
Sidereal period ~ 2350 a
Inclination of the orbit plane 89.5 °
Perihelion January 29, 1999
Orbital velocity in the perihelion 39.3 km / s
history
Explorer J. Tilbrook
Date of discovery January 12, 1999
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 1999 A1 (Tilbrook) is a comet that was observed in 1999.

Discovery and observation

The comet was the evening of 12 January 1999 (local time) by amateur astronomers Justin Tilbrook in Clare north of Adelaide in South Australia with a 200 mm - f / 6 - Reflector discovered. It was his second comet discovery, about a year and a half after his last. During this period he searched for comets for a total of 130 hours. The amateur astronomer and comet discoverer Don Edward Machholz had already searched the sky near the comet on December 9, 1998 and again on January 3, 1999, but he must have escaped it.

Tilbrook was immediately sure that it wasn't a known comet. He contacted two other Australian astronomers to have his discovery confirmed and then informed the IAU , which officially confirmed the discovery the next day.

Although relatively close to Earth , the comet was only a faint object with a magnitude of about 10 mag at the time of its discovery. As it moved further south, so that it was never visible to observers in the northern latitudes of the northern hemisphere , its brightness continued to decrease rapidly. The last position was determined on February 25th at the Observatorio Astronómico Los Molinos in Uruguay . An attempt to find the comet again in March was unsuccessful, its brightness must have been below 13 mag at this time.

Justin Tilbrook (along with three other comet discoverers) received the Edgar Wilson Award in 1999 for his comet discovery .

Orbit

An elliptical orbit could be determined for the comet from 70 observation data over a period of 43 days , which is inclined by around 89 ° to the ecliptic . Its orbit is thus almost perpendicular to the orbits of the planets . At the point of the orbit closest to the sun ( perihelion ), which the comet last traversed on January 29, 1999, it was located at a distance of 109.3 million km from the sun in the area of Venus' orbit . As early as December 25, 1998, it had come close to earth to around 0.30  AU / 45.3 million km.

In the vicinity of the descending node of its orbit, the comet Tilbrook moved around January 2, 1999 in the immediate vicinity of the earth's orbit, and in fact at a distance of only about 0.068 AU / 10 million km. However, the earth had already passed this point three weeks earlier on December 11, 1998.

The comet moves in an extremely elongated elliptical orbit around the sun. According to the orbital elements , which are afflicted with a certain uncertainty, its orbit had an eccentricity of about 0.9954 and a semi-major axis of about 159 AU some time before the passage of the inner solar system in 1999 , so that its orbit period was about 2005 years. The comet could therefore have last appeared in antiquity around the year -5 ( uncertainty ± 40 years), although it apparently remained undetected due to its low brightness. Due to the gravitational pull of the planets, in particular due to the close passage of Jupiter on January 8, 1999 at a distance of 4 ¾ AU, the orbital eccentricity was increased to about 0.9960 and the semi-major axis to about 181 AU, so that its orbital period is about 2435 Years increased. When it reaches the point of its orbit furthest from the sun ( aphelion ) around the year 3215 (uncertainty ± 30 years) , it will be about 54 billion km from the sun, about 360 times as far as the earth and 12 times as far like Neptune . Its orbit speed in the aphelion is only about 0.10 km / s. The next perihelion of the comet is expected to take place around the year 4435 (uncertainty ± 55 years).

See also

Web links

Individual evidence

  1. ^ Comets Discovered from South Australia. Astronomical Society of South Australia, accessed June 2, 2016 .
  2. ↑ A Tale of Discovery - Tilbrook Strikes Again! Astronomical Society of South Australia, accessed June 2, 2016 (with photo of J. Tilbrook and the comet).
  3. ^ DWE Green: IAUC 7084: 1999 A1; C / 1998 P1. IAU Central Bureau for Astronomical Telegrams, accessed June 2, 2016 .
  4. ^ C / 1999 A1 (Tilbrook). IAU Minor Planet Center, accessed June 3, 2016 .
  5. ^ J. Shanklin: The comets of 1999. In: Journal of the British Astronomical Association. Vol. 119, 2009, pp. 317-339 ( bibcode : 2009JBAA..119..317S ).
  6. ↑ NASA JPL Small-Body Database Browser: C / 1999 A1 (Tilbrook). Retrieved June 1, 2016 .
  7. ↑ A. Vitagliano: SOLEX 11.0. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .