Circular 2004/3
Tim Cooper
Director: Comet & Meteor Section
2004 September
I have completed my paper for the Symposium in October, titled 'An Analysis of Comet Brightness Behaviour from ASSA Observations'. The paper is co-authored with Mike Begbie, who made a large number of observations over the last 10 years. The paper is based on observations made by Mike Begbie, Tim Cooper, Tom Lloyd Evans, Mauritz Geyser, Trevor Green, Tony Jones, Gerrit Penning, David Pringle-Wood, Theo Smith, Magda Streicher, Cliff Turk and Koos van Zyl. If you do not intend to attend the Symposium let me know and I will email a copy (to those who contributed observations).
The following comets and meteors can be observed in the last four months of 2004.
Comet Machholz C/2004 Q2
This comet is Machholz's tenth discovery, and is currently located in Eridanus, just west of Lepus. It remains well placed for observation until the end of the year, and indeed until mid January, when it moves rapidly northward. Currently about magnitude 10.5, it should brighten to magnitude 9 by end September. The orbital elements for calculating an ephemeris are: T = 2005 January 27.370, q=1.28614, e=1.000, i=38.326, peri=14.807, node=95.921 (2000)
Comet LINEAR C/2003 K4
In the next week this comet plunges into the sun's glare. It has been well observed so far by Koos van Zyl, Mike Begbie and myself. It will reappear in the morning sky in November, probably around magnitude 8, and should be followed until late in the year as it crosses the False Cross.
Comet LINEAR C/2003 T4
This comet brightens to magnitude 10 by year end on its way to perihelion in April 2005. However it is a northerly object, and will only become really suitable for observation after perihelion as it crosses Sculptor and Pheonix, likely at magnitude 6.
September Taurids ?
Magda Streicher has been observing this potential activity after it was first reported in the September 2002 Sky and Telescope by Steve O'Meara. The meteors were said to be fast, emanating from a radiant near 37 Tauri, (04h05, +22) and were observed in both 2001 and 2002. Attempts so far to confirm its existence have been largely negative, so this year Magda and I will make a special effort to observe it. We would appreciate any other experienced observers doing likewise. All meteors must be plotted. Any activity is expected to peak on the morning of September 14.
Polish observers analysed 400 hours of observations between 1996 and 2000, and could find no trace of any activity, so if the activity exists, it is genuinely new. To complicate the issue there is also potential activity from the Aries-Triangulids, said to reach maximum on September 12 from a radiant at 02h, +29. Then Alastair Macbeath drew attention to a radio peak on September 17, with a possible radiant of visual meteors from Gemini/Orion. Clearly, to investigate what is going on or not in this region, all meteors need to be plotted. Please submit your plots, with path length and directions as accurately as possible, along with each meteors time of observation, magnitude, colour and speed.
Orionids
Conditions favour observation with maximum on October 21. The 60% moon sets just after 1 am. However, the peak is usually quite broad, with a number of possible submaxima before and after the main peak. The moon setting later each morning will hamper observation after the predicted peak. The zenithal hourly rate at maximum is around 25-30. Observation can continue until about 04h00 each morning (note SAST, Pretoria time)
Leonids
Conditions over the period November 16-19 are favourable this year. However, no enhanced activity is predicted, and the normal peak predicted for early morning of November 17 is probably the best opportunity to see Leonids in 2004. I would encourage observing to see if anything unexpected occurs, or simply to establish the rates now that the series of outbursts is over. Observe from 02h00 to 04h00 each morning.
Alpha Monocerotids
This shower is normally inactive, but showed outbursts in 1925, 1935, 1985 and 1995. In the latter case the entire outburst lasted only 30 minutes. Please make a special effort to observe this year. The radiant is at 07h48, +01, rises at about 22h00 and is highest just before dawn. Any peak this year, if it occurs, is expected on the morning of November 21. The gibbous moon will set about 2am.
December Phoenicids
Alastair MacBeath in the UK has reported on the history of this shower recently. It has only been observed on one occasion, in 1956, including several ASSA members at that time. Observations to confirm whether there is any activity now are required. Any activity is predicted to peak on December 6 just before dawn. All meteors should be plotted.
Geminids
Usually our most reliable shower, the Geminids show a ZHR of about 80 at maximum on the morning of December 13. These slow, graceful meteors often show a sparkling appearance, and are a joy to watch. The moon, just after new, will not interfere at all. The stream is mass-sorted, so while rates on December 14 will be lower, the meteors are about a magnitude brighter. Rates climb more slowly in the days leading up to maximum, and drop off quickly after. By the morning of December 15 rates are already well down. Conditions can hardly be better this year, so don't miss this opportunity.
Clear Skies
Tim
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