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.
Comets
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
Tim
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