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(meteorobs) Meteor Activity Outlook for November 9-15, 2001
The moon is new on Thursday November 15th. This weekend the waning
crescent moon will rise during the dark mid-morning hours. Next week
the moon becomes less of a problem as it approaches the sun as seen in
our skies. 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 18 for the Northern Hemisphere and 10
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 November 10/11. The
positions do not change greatly day to day so they may be used during
this entire period.
The Delta Eridanids are listed among the radiants of the Dutch Meteor
Society. This very weak shower peaks on November 12 with an estimated
ZHR (zenith hourly rate) of 1. The radiant position lies at 03:36 (054)
-02. This area of the sky lies in northwestern Eridanus a few degrees
south of the 4th magnitude star 10 Tauri. Any slow meteor from this area
or southwestern Taurus may be a shower member. Do not confuse this
activity with that of the antihelion radiant located to the northeast.
The antihelion radiant will produce much more activity. These meteors
will be best seen near midnight local standard time when it lies on the
meridian and is highest in the sky.
The Antihelion radiant is now located at 04:08 (064) +21. This area of
the sky is located in central Taurus close to the bright orange star
Aldebaran (Alpha Tauri). Any slow to medium speed meteor from Taurus 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 and is
highest in the sky. At this time expect to see at least 5 shower members
per hour from most locations. We are now starting to see an increase in
the antihelion activity as the earth encounters debris from comet 1P
Encke. 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 Zeta Puppids is another radiant listed among the radiants of the
Dutch Meteor Society. This weak shower peaks on November 13th from a
radiant located at 07:40 (115) -42. This area of the sky is located in
southern Puppis 3 degrees southwest of the 2nd magnitude star Zeta
Puppi. This radiant is better placed for observers located south of the
equator when it is seen much higher in the sky. These observers may see
2-3 shower members per hour at maximum. The radiant is best placed in
the sky near 0400 when it lies highest in the sky. Any shower members
would be of medium speed if seen far from the radiant and high in the
sky. If seen close to the radiant or low in the sky they would appear to
move more slowly.
The Northern Apex radiant is now located at 09:16 (139) +29. This
position lies in northeastern Cancer, less than 10 degrees northwest
form the Leonid radiant. 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 northern Cancer, southeastern Lynx or northwestern Leo
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. It will be difficult if not impossible to separate these
meteors from the early Leonids. Both radiants produce swift, often
trained meteors. At this early date odds are that any activity will
belong to the northern apex radiant and not the Leonids.
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 09:16 (139) -01. This position lies in western Hydra,
some 2 degrees west of the 4th magnitude star Tau2 Hydrae. 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, western Sextans or southeastern Cancer could be a candidate from
this source. Rates should be close to 2 per hour from most locations.
Leonid activity begins this week from a radiant located at 09:48 (147)
+25. This area of the sky is located only 2 degrees west of the 3rd
magnitude star Epsilon Leonis. As stated above, this area of the sky
also contains the northern apex radiant, which will be the more active
radiant at this time. Current Leonid rates are expected to be only 1-2
shower members per night. The radiant does not rise until midnight from
most locations so it is impossible to see any Leonid activity during the
early evening hours. The Leonids are very swift meteors when seen far
from the radiant and high in the sky. They will appear to move more
slowly if seen near the radiant or low in the sky. A special Leonid
outlook will be published soon.
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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