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(meteorobs) Meteor Activity Outlook for October 12-18, 2001
The moon is new on Tuesday October 16th. Morning observations will be
slightly affected by moonlight early in this period while the evening
will still be nice and dark. This week and next will offer the best
opportunities for meteor observing this month. The estimated total
hourly rates for evening observers this week should be near 3 for those
in the Northern Hemisphere and 1 for those in the Southern Hemisphere.
For morning observers the estimated total hourly rates should be near 16
for the Northern Hemisphere and 7 for those located in the Southern
Hemisphere. These rates assume that you are watching from rural areas
away from all sources of light pollution. The actual rates will also
depend on factors such as personal light and motion perception, local
weather conditions, alertness and experience in watching for meteor
activity. The positions listed below are exact for Saturday night/Sunday
morning October 13/14. The positions do not change greatly day to day so
they may be used during this entire period.
The Antihelion radiant is now located at 02:24 (036) +14. This area of
the sky is located in southern Aries 10 degrees southeast of the 2nd
magnitude star Hamal (Alpha Arietis). Any slow to medium speed meteor
from southern Aries or northeastern Cetus may be a good candidate for
this shower. This area of the sky is best placed near 0200 local
daylight time (0100 local standard time) when it lies due south on the
meridian. At this time expect to see perhaps 1 per hour from all
locations. Unlike most of the annual showers the antihelion radiant is
produced by debris from unknown sources orbiting in a direct motion like
the earth. These sources are most likely asteroids, which produce stony
and metallic debris whose density is much greater that produced by
comets. This debris collides with the earth on the inbound portion of
its orbit, before its closest approach to the sun. Therefore we best see
them just after midnight when we are facing the direction from which
this activity appears. The antihelion radiant is active all year from an
area of the sky nearly opposite that of the sun. The radiant will travel
approximately one degree eastward per day and travels through many
different constellations over the course of a year. Observers who share
their reports with the International Meteor Organization (I.M.O.)
should label these meteors as "North or South Taurids", depending if
they appear to radiate from north or south of the ecliptic.
The Orionids are increasing in strength as we approach the October 21
maximum. The current rates would still be low, most likely close to 1
shower member per hour. The radiant position lies at 06:04 (091) +15
which places it in northeastern Orion, very close to the 4th magnitude
Nu Orionis. With an entry velocity of 66 km/sec. the Orionid meteors are
swift when seen far from the radiant and high in the sky. They will
appear to move slower if seen close to the radiant or near the horizon.
The radiant lies due south at dawn and activity is best seen during the
hours just before the arrival of dawn when the radiant lies highest in
the sky. This shower is seen equally well from both hemispheres.
The Epsilon Geminids are now active from a radiant located at 06:32
(098) +27. This area of the sky lies in western Gemini 3 degrees
northwest of the 3rd magnitude star Epsilon Geminorum. This position is
fairly close to the Orionid radiant so care should be taken with shower
association. Both showers produce similar appearing meteors. Maximum
activity is expected on the 18th so rates should be 1-2 meteor per hour
this week. These meteors are best seen just before dawn with the radiant
lies high in the eastern sky. This shower is slightly better seen by
those located in the Northern Hemisphere. Beyond 40 degrees south the
radiant does not climb very high in the northern sky and activity will
be limited.
The Delta Aurigids reached maximum activity on Wednesday October 10.
Once again this is not a sharp maximum so rates should much the same all
this week. Expected rates would be close to 1 shower member per hour as
seen from the Northern Hemisphere. The radiant is located at 06:40 (100)
+50 which lies on the Auriga/Lynx border some 8 degrees northeast of
the 2nd magnitude star Menkalinan (Beta Aurigae). This area of the sky
lies close to the zenith at dawn for observers in the mid Northern
Hemisphere. Shower activity is also visible from the south tropic
latitudes but not beyond 40 degrees south latitude. These meteors are
swift when seen far from the radiant and high in the sky. They will
appear to move more slowly if seen near the radiant or near the horizon.
Do not confuse these meteors with those similar appearing meteors from
the northern apex.
The Northern Apex radiant is now located at 07:24 (111) +37. This
position lies in extreme eastern Auriga 5 degrees northwest of the 2th
magnitude star Castor (Alpha Geminorum). This area of the sky is best
placed for viewing during the last dark hour before dawn. Since this
radiant is diffuse any meteors from eastern Auriga, southwestern Lynx,
or northern Gemini could be a good candidate. As seen from the Northern
Hemisphere this source should produce at least 2-3 meteors per hour
during the last few hours before dawn. Rates seen from the Southern
Hemisphere would be much less at 0-1 per hour due to the low radiant
altitude seen south of the equator.
Like the antihelion radiant both apex radiants are active all year long
and travel approximately one degree eastward per day. Unlike the
antihelion debris these particles orbit the sun in a retrograde motion
opposite that of the earth and are most likely produced by unknown
comets. They strike the earth after their closest approach to the sun.
Since they are moving in opposite directions these particles strike the
earth at tremendous velocities often creating bright meteors with
persistent trains. These particles strike the earth on the morning side
of earth and are best seen just before morning twilight while the sky is
still perfectly dark. There are meteors with a zero inclination that
radiate precisely from the apex point on the ecliptic, exactly 90
degrees west of the sun. These meteors are rare though as the earth
orbits the sun it "sweeps clean" much of the material that shares the
same orbit. Much more debris is located just north and south of the
earth's orbit with slightly higher or lower inclinations. This creates
the northern and southern branches of the apex activity. Meteors from
both branches are normally included in the sporadic count but should
also be noted in some manner as to which branch of the apex complex they
appear to radiate.
The Southern Apex source lies exactly 30 degrees south of its northern
counterpart at 07:24 (111) +07. This position lies in central Canis
Minor only 1 degree south of the 3rd magnitude star Gomeisa (Beta Canis
Minoris). 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 Canis Minor could be a candidate from this source. Rates
should be close to 1 per hour from most locations.
The Sporadic rates for the Northern Hemisphere are now near 8 meteors
per hour during the last hours before dawn from rural observing sites.
This estimate and the morning estimate for the Southern Hemisphere does
not include the apex meteors listed above. During the evening hours
perhaps 3 random meteors can be seen per hour from the Northern
Hemisphere. Rates seen from the Southern Hemisphere are now at their
annual low with perhaps 4 random meteors being seen per hour during the
late morning hours and 1 per hour during the evening.
Clear Skies!
Robert Lunsford
AMS Visual Program Coordinator
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