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(meteorobs) Meteor Activity Outlook for December 15-21, 2000


                Meteor Activity Outlook for December 15-21, 2000
         Date: 
                Thu, 14 Dec 2000 14:51:01 -0800
         From: 
                Robert Lunsford <lunro.imo.usa@home.com>
The moon reaches its last quarter phase on Monday December 18. At this
time it will be limited to the morning sky allowing evening observers a
chance to watch in dark conditions. Only the Antihelion meteors can be
viewed this week in moonless skies. It may be best to save your
observing efforts for the upcoming Ursid display, which could be much
better than normal this year. The positions listed below are exact for 
Saturday night/Sunday morning December 16/17. The positions do not
change greatly day to day so these positions may be used during this
entire period.

The Antihelion radiant is now located at  06:40 (100) +23. This area of
the sky is located in central Gemini between the bright stars Upsilon
and Delta Geminorum.  Any slow meteor from this area is a good 
candidate for this shower. This area of the sky is best placed near 0100
local time when it lies on the meridian. At this time expect to see
perhaps 2 to 3 meteors per hour from this source. 

The Zeta Puppids may be active from a radiant located at 09:24 (141)
-49. This position lies in a rich star field in central Vela just north
of the "False Cross". Activity from this radiant would be difficult to 
detect from the Northern Hemisphere. Those situated south of the equator
have a much better chance of seeing any of this activity. This radiant
is highest in the sky near 0300 local time. Shower members would 
appear to travel slowly if seen near the radiant or low in the sky.
Those appearing far from the radiant and high in the sky would be of
medium velocity.

The Northern Apex is now located at 11:40 (175) +17. This position lies
in eastern Leo just 2 degrees northwest of the bright star Denebola
(Beta Leonis). Since this radiant is diffuse any meteors from eastern 
Leo, western Virgo, northwestern Coma Berenices would be a good
candidate. As seen from the Northern Hemisphere this source should still
be active producing 2-3 meteors per hour near dawn. From the Southern
Hemisphere this source would be slightly lower in the sky producing
perhaps 1-2 meteors per hour. These meteors should be reported as "COM"
by observers reporting to the IMO.

The Southern Apex source lies exactly 30 degrees south of its northern
counterpart at 11:40 (175) -13. This position lies in a rather blank
area of the sky in the constellation Crater. Like the northern apex
these meteors are best seen toward dawn when the radiant lies highest
above the horizon in a dark sky. Any meteor from Crater, Corvus, or
southwestern Virgo could possibly be a good candidate from this source.
As seen from the Northern Hemisphere this source should produce 1-2
meteors per hour near dawn. Rates seen from the Southern Hemisphere may
be a bit higher reaching 2-3 per hour.

The Ursid rates reach one per hour on December 17. Due to its high
northern location the Ursid radiant exhibits very little movement. The
listed radiant is located at 14:28 (217) +76. This position is located 
close to the bowl of the "Little Dipper" near the bright orange star
Kochab. The radiant is circumpolar meaning that it is always in the sky
for most northern latitudes. Unfortunately this display is nearly 
invisible from locations south of the equator. Activity can be seen at
all hours of the night but the late morning hours are most favorable as
the radiant reaches its highest nighttime altitude just before dawn.  
Low activity can be expected from this radiant until the 22nd when it is
expected to reach maximum between 06 and 10 hours UT. This timing would
favor North America as it covers 1am to 5am EST and 10pm to 2am PST.
Normal Ursid hourly rates at maximum activity are near 10. There exists
the possibility that the 2000 display may be enhanced producing several
times this amount. It seems that the dust trails produced by comet
Tuttle encounter the earth near perihelion and also 6 years after the
comet has passed the sun. The last perihelion passage of comet Tuttle
was in 1994 so this year may provide some interesting surprises. The
normal foul weather and holiday season prevent good monitoring of this
display year to year. I would strongly encourage observers to monitor
the skies December 21-23 to help us obtain a good activity curve for
this years display.

The Sporadic rates for the Northern Hemisphere should still be strong.
One would expect to see perhaps 5-7 random meteors per hour during the
last hours before dawn from rural observing sites. Lunar interference
accounts for the lower figure this week. During the evening hours
perhaps 3-4 random meteors can be seen per hour. Rates seen from the
Southern Hemisphere are on the upswing and nearly match those rates seen
from the north.

Clear Skies!
Robert Lunsford
AMS Visual Program Coordinator
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