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(meteorobs) Meteor Activity Outlook for June 22-28, 2001



The moon is now new and soon will be a waxing crescent and limited to
the evening sky. This week will offer more good viewing to the early
morning observer who will see the best activity. This is prime observing
time for observers in the far Southern Hemisphere as the nights are at
their longest this time of year. Just the opposite occurs for far
Northern Hemisphere observers who now suffer through short nights and
eternal twilight. This is the one time of the year when man-made
satellites may be seen all night long in the Northern Hemisphere. Even
from middle northern latitudes satellites may be glimpsed near midnight 
low in the northern skies.

The estimated total hourly rates for evening observers this week should
be near 1 for those in Northern Hemisphere and 2 for Southern Hemisphere
observers with some slight lunar interference. For morning observers the
estimated total hourly rates should be near 8 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 except for the moon. 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 June 23/24. The positions do not change greatly day
to day so these positions may be used during this entire period.

The June Bootids (Pons-Winneckids) came roaring back to life on June 27,
1998 when ZHR's of 50-100 where reported over a vast area of the earth.
While it is uncertain that any activity will reoccur from this radiant
this year one should not miss the opportunity to observe any activity
from this elusive shower. Maximum activity is predicted to occur on
Tuesday evening/Wednesday morning June 26/27 near 0700 Universal Time.
This favors North America and the northern Pacific areas. Some activity
may also be visible from the northwestern portion of South America. For
North American time zones this corresponds to 0300 EDT, 0200 CDT, 0100
MDT, midnight PDT, 2200 (10pm on 6/26) ALA, and 2100 (9pm on 6/26) HAW. 
The moon will be at first quarter and will set between midnight and 0100
for most locations. Only the US mainland, Canada, Central and South
America will be able to observe at this time in skies free of moonlight. 
On June 27 the radiant will be located at 14:56 (224) +48. This area of
the sky is located in a remote area of northern Bootes some 8 degrees
north of the 3rd magnitude star Beta Bootis. This area of the sky is
best placed near the zenith for mid northern observers as soon as it
becomes dark. As the night progresses the radiant sinks into the
northwest becoming quite low after 0400. This is not a problem for those
in high northern latitudes as morning twilight interferes before this
time. From European, African, and  Mid Eastern longitudes the best time
to watch would be as late as possible on the morning of June 27. For Far
Eastern and Australian longitudes the best time to watch would be after
dusk on June 27. With an entry velocity of only 18 kilometers per second
true shower members would appear to move quite slowly no matter where 
they appear in the sky.

The Antihelion radiant is now located at 19:08 (287) -22. This area of
the sky is located in northern Sagittarius only 1 degree north of the
the 3rd magnitude star Pi Sagittarii. Any slow to medium speed meteor
from northern Sagittarius, southern Aquila, or southern Scutum 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 on the
meridian. At this time expect to see perhaps 1 per hour from locations
in the Northern Hemisphere and 2 meteors per hour from the Southern
Hemisphere. 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. It is easiest to
simply list these meteors as "ANT" but a majority of meteor
organizations prefer that you list them from the constellation in which
the radiant is currently located or the constellation where the shower
reaches maximum activity. For instance those who share reports with the
IMO should now label these meteors as Sagittarids (SAG) and Gamma
Sagittarids for the DMS.

The Tau Aquarids are listed among the radiants of the Dutch Meteor
Society. Their studies indicate a ZHR of 3 at maximum activity on June
29. Current rates would approximately 1 per hour for observers south of 
30 degrees north latitude. The radiant position is 22:32 (338) -14. This
position is located in central Aquarius 3 degrees west of the 4th
magnitude star Tau 2 Aquarii. With an entry velocity of 63 kilometers 
per second these meteors would move swiftly if seen far from the radiant
and high in the sky. Like the Apex radiants this activity would be best
seen during  the last few hours before dawn.

The Northern Apex radiant is now located at 00:08 (002) +16. This
position lies on the Pegasus/Pisces border just 1 degree northwest of
the 3rd magnitude star Algenib (Gamma Pegasi). This is the southeastern 
star in the "Great Square of Pegasus". 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 Pisces or eastern Pegasus
could be a good candidate. As seen from the Northern Hemisphere this
source should produce at least 1 meteor per hour during the last few
hours before dawn. Rates seen from the Southern Hemisphere should be 
similar. 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 00:08 (002) -14. This position lies in southwestern Cetus
some 8 degrees northwest of the 2nd magnitude star known as Deneb Kaitos
or Diphda (Beta Ceti). 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 southeastern Aquarius, northern Sculptor, or
western Cetus could  be a candidate from this source. Rates should be
close to 1 per hour as seen from the lower Northern Hemisphere and all
of the Southern Hemisphere. Those reporting data to the Dutch Meteor
Society should now list these meteors as Tau Cetids.

The Sporadic rates for the Northern Hemisphere are now at their lowest
levels of the year. One would expect to see perhaps 5 random 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
1 random meteor can be seen per hour from the Northern Hemisphere. Rates
seen from the Southern Hemisphere would now be slightly better than
those seen in the Northern with perhaps 6 random meteors being seen per
hour during the late morning hours and 2 per hour during the evening.

Clear Skies!
Robert Lunsford
AMS Visual Program Coordinator
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