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(meteorobs) Meteor Activity Outlook for Nov. 28-Dec. 4, 2003



The moon reaches its first quarter phase on Sunday November 30. At this time
the moon lies ninety degrees east of the sun and will set near local
midnight. Later in this period the waxing gibbous moon will linger in the
morning sky causing more interference to the prime time viewing hours. The
estimated total hourly rates for evening observers this week should be near
two for those in the Northern Hemisphere and one in the Southern Hemisphere.
For morning observers the estimated total hourly rates should be near
sixteen for those located in the Northern Hemisphere and twelve for those 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 meteor activity.
Rates are reduced during the evening hours due to moonlight.

The radiant positions listed below are exact for Saturday night/Sunday
morning November 29/30. The radiants do not change greatly day to day so the
given positions may be used during this entire period. Most star atlases
(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 positions below are listed in a west to
east manner in order of right ascension (celestial longitude). The positions
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 December Phoenicids (PHO) is an obscure shower that produced an outburst
in 1956. A few shower members are reported each year by observers in the
Southern Hemisphere. Conditions are poor this year with moonlight obscuring
the entire activity period. Nevertheless, should your evening skies be
clear, especially on December 6, one should check for activity from this
radiant. The radiant is currently located at 00:52 (013) -55. This position
lies in central Phoenix, seven degrees northwest of the zero magnitude star
Achernar (Alpha Eridani). These meteors are best seen near 2000 (8:00 pm)
local standard time when the radiant lies highest above the horizon. Due to
the far southern declination (celestial latitude) this shower is visible
only from the northern tropical locations and areas southward. At 18 km/sec.
the December Phoenicids produce slow meteors.

The Delta Eridanids (DER) are listed among the radiants of the Dutch Meteor
Society. This shower peaked on November 13 with an estimated ZHR of only
one. The radiant is located at 04:40 (070) +01. This position lies on the
Eridanis/Taurus/Orion border some twelve degrees northwest of the zero
magnitude star Rigel (Beta Orionis). These meteors are best seen near 0000
(midnight) local standard time when the radiant lies highest above the
horizon. At 31 km/sec. the Delta Eridanids produce meteors of average and
slow velocities.

The Antihelion radiant is now centered at 05:32 (083) +23. This area of the
sky is located in eastern Taurus, seven degrees southeast of the second
magnitude star El Nath (Beta Tauri). Since this radiant is large and
diffuse, any slow to medium speed meteor from northeastern Orion, southern
Auriga or eastern Taurus could be a candidate for this shower. The center of
this area 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 3 shower
members per hour from areas north of the equator and 2 per hour for
locations south of the equator.

Unlike most of the annual showers the antihelion source is produced by
debris from unknown objects orbiting in a direct motion like the earth.
These objects are most likely asteroids, which produce stony and metallic
debris whose density is much greater than material produced by comets. This
material 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 source is active all year from an area of the sky nearly
opposite that of the sun. The center of this source will move approximately
one degree eastward per day and travels through many different
constellations over the course of a year. It may make sense to list these
meteors as antihelions or "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 report to the IMO should list these meteors as Chi
Orionids (XOR).

The Monocerotids (MON) are not to be confused with the Alpha Monocerotids of
mid-November. This shower reaches a ZHR of one on November 28 and maximum
activity (ZHR three) on December 9. The radiant is currently located at
06:04 (091) +08. This position lies in eastern Orion only two degrees east
of the first magnitude star Betelgeuse (Alpha Orionis). These meteors are
best seen near 0200 local standard time when the radiant lies highest above
the horizon in a dark sky. At 42 km/sec. the Monocerotids produce meteors of
average velocity.

The Puppid/Velids (PUP) are most likely a continuation of the November Zeta
Puppid activity listed by the Dutch Meteor Society. This shower peaks near
December 7 with an estimated ZHR of ten. There are several suspected
radiants in this area combining to produce this activity. The main radiant
is located at 08:00 (120) -45. This position lies in southeastern Puppis,
five degrees south of the second magnitude star Zeta Puppi. These meteors
are best seen near 0400 local standard time when the radiant lies highest
above the horizon in a dark sky. Due to the far southern declination these
meteors are only visible from areas southward of latitude forty-five degrees
north. At 41 km/sec. the Zeta Puppids produce meteors of average velocity.

The Northern Apex radiant is now centered at 10:32 (158) +23. This position
lies in northern Leo, two degrees east of the third magnitude star Zeta
Leonis. This area of the sky is best placed for viewing during the last dark
hour before dawn when it lies highest in the sky. Since this radiant is
large and diffuse, any meteor from northeastern Cancer, northwestern Leo or
southwestern Leo Minor could be a candidate from this source. This source
should provide at least three meteors per hour for those in the Northern
Hemisphere and one per hour for those in the Southern Hemisphere.

Like the antihelion area, both apex areas 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. This is
not really a "shower" per se, but an artificial radiant created by the
Earth's motion through space. Meteors from both branches are normally
included in the sporadic count. I feel it is a worthy project to see if it
is possible to distinguish these meteors from the normal sporadic
background. On rare occasions there are meteors with a zero inclination that
radiate precisely from the apex point on the ecliptic, exactly 90 degrees
west of the sun. In simplistic terms, these meteors are seldom seen since
the Earth "sweeps clean" much of the material that shares the same orbit as
our planet. Much more material 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.

The Southern Apex source lies exactly 30 degrees south of its northern
counterpart at 10:32 (158) -07. This position lies in southern Sextans some
eight degrees southeast of the fourth magnitude star Alpha Sextantis. Like
the northern apex, these meteors are best seen toward dawn when the radiant
lies highest above the horizon in a dark sky. Since this radiant is also
large and diffuse, any meteor from western Hydra, southern Leo or Sextans
could be a candidate from this source. Rates would be now close to two per
hour regardless of your location.

The Sporadic rates for the Northern Hemisphere are now near their annual
peak. One would expect to see perhaps eight random meteors per hour during
the last hours before dawn from rural observing sites. This estimate and the
estimate for the Southern Hemisphere does not include meteors from the apex
radiants. During the evening hours perhaps two random meteors can be seen
per hour. Rates seen from the Southern Hemisphere would be approximately six
random meteors being seen per hour during the late morning hours and one
during the evening hours. Evening rates are reduced in both hemispheres due
to moonlight.

Clear Skies!
Robert Lunsford
AMS Operations Manager

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