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Circular 2006/1

Tim Cooper
Director: Comet & Meteor Section

2006 January

Feedback

I have drafted the Section report for 2005.  Observations of seven comets and six meteor showers were received from Magda Streicher, Mike Begbie, David Pringle-Wood, Cliff Turk, Karen Koch, Tony Jones, Mauritz Geyser, Koos van Zyl and myself. These nine contributors are heartily thanked.  If you still have unreported observations please send these soonest.

News

The Stardust probe passed within 236 km of comet Wild 2 in January 2004, capturing thousands of particles from the comet in the process. The probe will return to earth in January 2006, parachuting down in the Utah desert. A team headed by Dr Peter Jenniskens, who has twice visited us in South Africa, will monitor the descent from a DC-8 aircraft. The reentry will mimic the action of a meteor, and Jenniskens quoted "The carbon from the heat shield will react in the shockwave, making new molecules that would have seeded earth at the time of the origin of life. The carbon in comet dust could have done the same.  The samples brought back from comet Wild-2 will tell us is what carbon compounds are in cometary dust."

Comets

Talking of comets the following comets are suitable for observation:

Comet C/2004 B1 LINEAR

This comet reaches perihelion in February 2006, and closest approach to earth in May, when it might reach 10th magnitude.  During May-June the comet moves north through Aquila into Hercules. The orbital elements are: T=2006 Feb 7.885, q=1.60196, e=1.000, i=114.0926, peri=327.8945, node=272.7944.

Comet C/2005 E2 McNaught

This comet is currently around magnitude 12, small and very condensed (my observations). It is located in Capricornus and should brighten to magnitude 10 before becoming lost in the solar glare. The orbital elements are: T=2006 Feb 23.3644, q=1.5176, e=1.000, i=16.9916, peri=40.0449, node=347.8239.

Comet 41P Tuttle-Giacobini-Kresak

Dan Green of the ICQ has requested observations of this comet and observers are requested to pay particular attention to it in 2006. It has a history of rapid brightening pre-perihelion, was rather bright at its last two apparitions, and at its 1973 apparition underwent two large outbursts of 9-10 magnitudes peaking at magnitude 4-5. The orbital elements are T=2006 June 11.2754, q=1.0478, e=0.6604, i=9.2295, peri=62.1972, node=141.0898. The 2006 apparition is very similar to that of 1973. Comet 41P is expected to reach magnitude 10 around perihelion on June 11, but in light of above may well be brighter. It passes from Cancer into Leo in early June and spends the rest of the month in this constellation.

Comet 71P Clark

This comet will be well placed for the southern hemisphere.  It reaches perihelion on June 7 and opposition a week later, when it will likely be magnitude 10 or 11 and at declination -40.

Comet 73P Schwassmann-Wachmann

This comet makes a very favourable return in 2006. Observers will no doubt recall its 1995 outburst when, shortly after perihelion, it underwent an outburst to magnitude 5.5.  One of the first to see it was Jannie Smit as the comet wandered through the field of variable star RS Librae. Close inspection of the nucleus with large telescopes revealed it had split into at least three fragments, the largest, easternmost fragment known as Fragment C. The individual fragments were followed at the 2000/1 apparition, and may still be visible this time.  The orbital elements for Fragment C are T= 2006 June 6.9497, q=0.9391, e=0.6932, i=11.3960, peri=198.8039, node=69.8955.

In 2006, comet 73P passes closest to earth on May 17 on its way to perihelion on June 6. Its brightness is rather uncertain but there are good grounds to expect that it will become visible to the naked eye or an easy binocular object. The visibility of the other fragments is also uncertain. Observers should monitor the brightness of the comet carefully from about March onwards. On the morning of May 8 it will be in the low power field of the Ring Nebula

 

Meteor Showers

Meteor showers in the first months of 2006 are largely lost to the moon, with the alpha Crucids, alpha Centaurids and gamma Normids all affected.  The following showers are favourable in the first half of the year.

Delta Pavonids

This is a poorly studied minor shower, with maximum around April 6 or 7. The meteors are the debris of comet Grigg-Mellish and originate from a radiant at 20h32, -63.  The meteors are fast, mainly blue-white in colour and often bright, with common persistent trains.  The radiant is high enough to observe from midnight until dawn, and the moon sets shortly after midnight.

Pi Puppids

This stream, the debris of comet 26P Grigg-Skjellerup, had notable outbursts in 1972, 1977 and 1982, which seemed to indicate some periodicity similar to the comet's orbital period of 5.3 years. Outside these years, the shower is virtually undetected. The comet was last at perihelion in November 2002 and next in 2008, so little is expected in 2006 from the shower. However, conditions favour observation, with no moon to speak of, and observations are encouraged in case something unexpected does happen.  The radiant is perfectly placed in the evening and observation can continue until about midnight.  Pi Puppids are very slow and often bright.

Eta Aquarids

Once again conditions are favourable for observation of the most active southern meteor shower.  Activity starts slowly in the last week of April, kicking upwards in the first days of May, and generally peaking on the mornings of May 5 or 6.  Activity can remain high for a few days thereafter.  New moon is on April 27, first quarter on May 5.  Since the radiant is only high enough to observe from about 3am local time, observations can continue until May 9 without any hindrance from the moon at all. This gives an ideal opportunity in 2006 to monitor the entire rise, maximum, and start of the decline in activity of this shower.  All observers are requested to give this shower priority.  The meteors are swift, often bright and the brighter members leave persistent trains. Very bright members display a definite green colour.  Observers should be careful to report separately any May Capricornids which are active at the same time.

 

I trust the above will provide interesting comet and meteor observing projects and look forward to receiving your observations.
Clear Skies,
Tim

 

 

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