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(meteorobs) Meteor Activity Outlook for February 1-7, 2002
The moon reaches its last quarter phase on Monday February 4. At this
time the moon will rise near midnight and be near the meridian at
sunrise. These are not the best conditions for viewing meteor activity.
You can overcome this obstacle by facing in a direction away from the
moon such as north or west. One could also try viewing during the
evening hours but the rates would be very low at that time. The
estimated total hourly rates for evening observers this week should be
near 1 for everyone regardless of location. For morning observers the
estimated total hourly rates should be near 3 for everyone regardless of
location. 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 meteor activity. Rates
are reduced by moonlight during this period.
The positions listed below are exact for Saturday night/Sunday morning
February 2/3. The positions do not change greatly day to day so these
positions may be used during this entire period. Most star atlas's
(available at science stores and libraries) will provide maps with grid
lines of the celestial coordinates so that you may find out exactly
where these positions are located in the sky. A planisphere or computer
planetarium program is also useful in showing the sky at any time of
night on any date of the year. Activity from each radiant is best seen
when it is positioned highest in the sky, either due north or south
along the meridian, depending on your location. Meteor activity is not
seen from radiants that are located below the horizon. The radiants
below are listed in a west to east manner in order of right ascension
(celestial longitude). The radiants listed first are located further
west therefore are accessible earlier in the night while those listed
last rise later in the night. This list also provides the order of
ascending velocity for each radiant with those listed first usually
being much slower than those last on the list. Velocity should not be
the prime factor for shower association as all showers can produce slow
meteors. Slow meteors can be produced from normally swift showers, such
as the Leonids, when meteors appear near the radiant or close to the
horizon. The true velocity is only revealed in shower members seen far
from the radiant and high in the sky.
The Alpha Carinids are listed among the radiants of the Dutch Meteor
Society. They are active for two weeks centered on January 30. The
listed maximum ZHR is only 2 so southern observers need to be especially
careful when determining shower association and random meteors may line
up and appear as shower members. The radiant is located at 06:28 (097)
-54. This area of the sky is located in western Carina only 2 degrees
southeast of the brilliant star Canopus (Alpha Carinae). This area of
the sky is too low for observers north of 30N latitude. Those south of
30N can try to see activity near 2200 (10pm) local time when the radiant
lies highest in the sky. With an entry velocity of 25 kilometers per
second, these meteors would appear to move slowly no matter where they
are seen in the sky.
The Delta Velids are another shower listed in the DMS radiant table.
They are active for a month from January 22 through February 21 when
maximum activity occurring on February 14. The listed ZHR is only 2 so
once again the chance of sporadic pollution is high. This means that
there is more of a chance that a random meteor will line up with the
radiant than an actual shower member. The radiant is located at 08:20
(125) -49 which place it in western Vela only 3 degrees southeast of the
2nd magnitude star Gamma Velorum. Again this is too far south to be seen
north of 30 degrees north latitude. Southern observers have the best
view of this activity when it reaches the meridian near 2300 (11pm)
local time. With an entry velocity of 35 kilometers per second these
meteors are only slightly faster than the Alpha Carinids.
The Alpha Hydrids reached maximum activity back on January 14. Random
shower members can still be seen from a radiant located at 09:48 (147)
-17. This area of the sky is located in Hydra some 10 degrees southeast
of the 2nd magnitude star Alphard (Alpha Hydrae). At this position the
radiant is accessible to most latitudes and is best seen near 0100 or
1am local time. Shower members would be rare with rates well below
one meteor per hour. With an entry velocity of 44 kilometers per second
these meteors would have a medium apparent velocity.
The Antihelion radiant is now located at 09:52 (148) +12. This area of
the sky is located in western Leo only 3 degrees west of the 1st
magnitude star Regulus (Alpha Leonis). Any slow to medium speed meteor
from eastern Cancer or western Leo could be a 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 2 shower members per hour from locations in the Northern
Hemisphere. Observers south of the equator will most likely be limited
to 1 per hour or less, owing to the lower radiant altitude. 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. Those who share reports with the I.M.O. should
label these meteors as Virginids (VIR).
The Omicron Centaurids are part of an group of radiants active in the
constellation of Centaurus during February. Unfortunately most of this
activity is weak and not well seen from northern latitudes. They are
active from January 31 through February 19 with maximum activity
occurring on February 14. Even at maximum activity rates are only 2 per
hour as seen from the Southern Hemisphere so current rates would be less
than 1 per hour. The radiant is located at 11:08 (167) -52 which places
it in western Centaurus some 12 degrees northwest of the 2nd magnitude
star Gacrux (Gamma Crucis). This part of the sky is best seen near 0300
local time when it lies highest in the sky. With an entry velocity of 51
kilometers per second these meteors would have a medium-swift apparent
velocity.
The Theta Centaurids are another member of the Centaurid complex active
in February. Located at 13:12 (198) -37 the Theta Centaurids are the
most northern of these radiants and accessible to observers south of 45
degrees north latitude. This position lies in western Centaurus 2
degrees southwest of 3rd magnitude Iota Centauri. This part of the sky
is best seen near 0500 local time. The maximum activity occurs on
February 14 with the ZHR reaches 4. Current rates would be 1 per hour
and perhaps 1 per night as seen from the Northern Hemisphere. With an
entry velocity of 60 kilometers per second these meteors would have a
swift apparent velocity.
The Alpha Centaurids are a strong minor shower visible only from the
northern tropics southward. They are active from January 28 through
February 21 with maximum activity occurring on February 8. Current rates
would be 2-3 per hour from locations in the Southern Hemisphere, where
the radiant rises high in the sky. The radiant is located at 13:32 (203)
-57 which places it in southern Centaurus 4 degrees south of the 2nd
magnitude star Epsilon Centauri. This part of the sky is best seen near
0500 local time when it lies highest in the sky. This may be during
morning twilight for far southern observers so they should watch during
the last few dark hours before morning twilight. With an entry velocity
of 56 kilometers per second these meteors would have a swift apparent
velocity.
The Northern Apex radiant is now located at 14:52 (223) -01. This
position lies in northern Libra some 10 degrees northwest of the 3rd
magnitude star Zubeneschamali (Beta Librae). 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 Libra, eastern Virgo,
southwestern Serpens Caput or southeastern Bootes could be a good
candidate for this shower. This source should provide 2-3 meteors per
hour during the last few hours before dawn regardless of your location.
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 14:52 (223) -31. This position lies in northeastern
Centaurus near the borders of Lupus, Libra, and Hydra. 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 northern Lupus,
northeastern Centaurus, southern Libra or eastern Hydra could be a
candidate from this source. Rates would be 3-4 per hour from the
Southern Hemisphere and 1-2 per hour from the Northern Hemisphere.
The Sporadic rates for the Northern Hemisphere are now in decline and
will do so until June. One would expect to see perhaps 5-6 random
meteors per hour during the last hours before dawn from rural observing
sites. During the evening hours perhaps 1-2 random meteors can be seen
per hour. Rates seen from the Southern Hemisphere would now be a bit
better than those seen in the Northern Hemisphere with perhaps 6-8
random meteors being seen per hour during the late morning hours and 2-3
during the evening hours. Moonlight interferes with morning rates.
Possible activity in Bootes-Corona Borealis-Serpens Caput? There have
been reports of activity in and around this area in late January and
early February. George Gliba was the first to notice this activity
during the mid 90's. Intensified video studies by the IMO in 2000
revealed two radiants; one in Serpens Caput and another located in
Corona Borealis during the first week of February. Observers are urged
to keep a look out for this activity now through mid-February. The two
IMO radiants are located at 15:32 (233) +30 and 15:44 (236) +13. The
northern radiant is located within the "crown" close to the star Beta
Coronae Borealis. The more southern radiant is located near the "head"
of Serpens 2 degrees south of Beta Serpentis. Another area of possible
activity would lie in eastern Bootes between Arcturus and Xi Bootis.
This area of the sky is too low until 0200 local time. The waning moon
will be a hindrance for the first week of the month. Any suspected
shower meteors would appear to move slowly if seen near the radiant or
near the horizon. Those seen high in the sky far away from the radiant
would appear to be swift. Meteors seen near the radiant would also be
short. If you are facing the radiants and see a long meteor close to the
radiant(s) then that meteor is sporadic or belongs to another shower.
Plotting, photographic, and video observations are of prime importance
to try to help us determine shower association. Your efforts in trying
to help us verify this activity and its exact radiant would be extremely
appreciated!
Clear Skies!
Robert Lunsford
AMS Visual Program Coordinator
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