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(meteorobs) Meteor Activity Outlook for October 26-November 1, 2001
The moon is full on Wednesday October 31st. This weekend the moon will
set during the early morning hours allowing a short opportunity to view
meteor activity under dark skies. The estimated total hourly rates for
evening observers this week should be near 2 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 9 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. Rates are
reduced due to moonlight during the evening hours. The positions listed
below are exact for Saturday night/Sunday morning October 27/28. 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 03:20 (050) +18. This area of
the sky is located on the Aries/Taurus border 8 degrees southwest of the
Pleiades, a bright "dipper shaped" star cluster well known to all star
gazers. Any slow to medium speed meteor from eastern Aries, western
Taurus, or northeastern Cetus may be a good candidate for this shower.
This area of the sky is best placed near 0100 local standard time when
it lies on the meridian. At this time expect to see perhaps 4 per hour
from all locations. We are now starting to see a slight increase in the
antihelion activity as the earth encounters debris from comet 1P Encke.
This additional material will push the antihelion activity up to 5-10
meteors per hour during the first half of November. 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 reached maximum activity on Sunday morning October 21.
Current rates should be less than 5 shower members per hour. Most shower
members are faint, being 3rd or 4th magnitude. Orionid fireballs do
occur and a majority of the brighter Orionids produce persistent trains.
The radiant position lies at 06:40 (100) +16 which places it in western
Gemini very close to the 2nd magnitude star Alhena (Gamma Geminorum).
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. Orionid
activity is best seen near 4am local standard time, when the radiant is
located on the meridian and lies at its highest point in the sky. This
shower is seen equally well from both hemispheres.
The Northern Apex radiant is now located at 08:20 (125) +34. This
position lies in southeastern Lynx 10 degrees northeast 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 southeastern Lynx, northern Cancer,
or northeastern Gemini could be a good candidate. As seen from the
Northern Hemisphere this source should produce 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 08:20 (125) +04. This position lies in extreme western
Hydra, some 5 degrees west of the serpent's head. 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 western Hydra, eastern
Canis Minor, or southern Cancer 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 2 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. Rates are reduced
due to moonlight during the evening hours.
Clear Skies!
Robert Lunsford
AMS Visual Program Coordinator
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