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Circular 2006/2

Tim Cooper
Director: Comet & Meteor Section

2006 April

The following opportunities exit for observations in the coming months. Conditions especially favour observation of comet Schwassmann-Wachmann 3, and the eta Aquarid meteor shower.


Comet C/2004 B1 LINEAR
This comet makes its 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 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. The outburst was shown to accompany fragmentation of the nucleus into at least four pieces. Since recovery in 2006 the comet has continued to fragment, numbering seven in March. The largest component is called fragment C and was at magnitude 10 in the first week of April. At the same time it was reported that fragment B had gone into outburst at magnitude 10.5, as a sharp object surrounded by slight haze. No doubt in the coming weeks we can expect an interesting performance.

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. 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 many other fragments is also uncertain. On the morning of May 8 it will be in the low power field of the Ring Nebula

Meteor Showers

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



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