(meteorobs) Meteor Activity Outlook for November 11-17, 2005

[Robert Lunsford]

The moon reaches its full phase on Wednesday November 16th. At this time the
moon will rise near sunset and set near sunrise. This weekend the waxing
gibbous moon will set during the late morning hours, leaving a small window
of opportunity to view under dark skies. The estimated total hourly rates
for evening observers this week should be near three for Northern Hemisphere
observers and two for those located in the Southern Hemisphere. For morning
observers the estimated total hourly rates should be near sixteen for
Northern Hemisphere observers and ten 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 meteor activity.  Evening
rates are reduced due to moonlight.

The radiant positions listed below are exact for Saturday night/Sunday
morning November 12/13. These positions do not change greatly day to day so
the listed coordinates may be used during this entire period. Most star
atlases (available at science stores and planetariums) 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 latitude. 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 further down the list rise later in
the night.

These are the showers that may be observed this week:

The Delta Eridanids (ERI) are listed among the radiants of the Dutch Meteor
Society. This shower peaks on November 12 with an estimated ZHR of only one.
With such low rates it is difficult to differentiate these meteors from the
sporadic background. Suspected shower members must have the correct velocity
versus radiant distance. This basically means that true shower members move
slowly when seen near the radiant and only slightly faster when seen further
away. The radiant is currently located at 03:44 (056) -02. This position
lies in northern Eridanus some twenty five degrees south of the famous
Pleiades star cluster. 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 Anthelion radiant is now centered at 04:24 (066) +21. This area of the
sky is located in central Taurus, seven degrees northwest of the first
magnitude orange star Aldebaran (Alpha Tauri). Since this radiant is large
and diffuse, any slow to medium speed meteor from northern Orion or 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 of year the normal anthelion activity is combined with
material from comet 2P Encke, producing the highest anthelion activity of
the year. Rates should be near three per hour from the Northern Hemisphere
and two per hour for observers south of the equator. With an entry velocity
of 30 km/sec., the average anthelion meteor would be of medium-slow speed.
Recent reports have shown above average rates with several fireballs
exceeding the brightness of the full moon. This activity should be followed
and reported as often as possible, even with the bright moon in the sky.

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. There
is also the possibility that some of this activity may be caused by the
"Jupiter family of comets", comets which have been altered by Jupiter's
gravity into much shorter orbits. 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 anthelions 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 send their reports to the International
Meteor Organization (IMO) should list these meteors as Southern (STA) or
Northern Taurids (NTA), depending on whether the meteors radiate from south
or north of the ecliptic.

The Alpha Monocerotids (AMO) reach maximum activity near 15:00 Universal
Time on November 21. This shower has the strange distinction of producing
short but very strong outbursts in several years ending in "5". Well guess
what, it's 2005! Unfortunately recent studies seem to indicate that no such
outburst will occur this year. Regardless, observers are urged to scan the
skies on the night of November 20/21 for any possible enhancement. The 1995
outburst only lasted thirty minutes but produce ZHR's as high as 420. The
Central Pacific regions are well place this year if indeed 15:00 is the
correct timing of a possible enhancement. As with the Leonids, a bright moon
will obscure many of the fainter meteors. Rates away from the 20/21 are
expected to be one shower member per hour or less. The radiant is currently
located at 07:24 (111) +02. This position lies in southwestern Canis Minor,
five degrees southwest of the zero magnitude star Procyon (Alpha Canis
Minoris). These meteors are best seen near 0300 local standard time when the
radiant lies highest above the horizon in a dark sky. At 65 km/sec. the
Alpha Monocerotids produce mostly swift meteors.

The Zeta Puppids (ZPU) are also listed among the radiants of the Dutch
Meteor Society. This shower peaks on November 13 with an estimated ZHR of
three. The radiant is currently located at 07:48 (117) -42. This position
lies in central Puppis four degrees southwest of the second magnitude star
Zeta Puppis. These meteors are best seen near 0400 local standard time when
the radiant lies highest above the horizon in a dark sky. Observers located
in the Southern Hemisphere have an advantage viewing this shower as the
radiant will rise higher into their sky allowing more activity to be seen.
At 41 km/sec. the Zeta Puppids produce meteors of average velocity.

The Leonids (LEO) reach a ZHR of one near November 14. Rates will remain low
until the night of November 17, when the Earth begins to pass through the
central portions of comet 55P Temple-Tuttle. Unfortunately the comet is now
heading for the outer portions of the solar system and the density of
particles near the Earth is now much lower than it was just a few years ago.
On top of that a full moon on November 16 will obscure the fainter Leonids,
making this display that much more difficult to view. Rates during late
morning hours should be near five Leonids per hour from the 17th through the
19th. The slight possibility exists of a minor outburst near 0100 Universal
Time on the 21st. This timing is well suited for Europe, Africa, and western
Asia. The Russian meteor scientist Mikhail Maslov states that this outburst,
produced by comet  55P Temple-Tuttle in 1167, will be quite weak, most
likely producing less than a dozen Leonid per hour at best. The radiant is
currently located at 09:56 (149) +23. This position lies in northwestern
Leo, four degrees west of the third magnitude star Zeta Leonis. The radiant
lies highest above the horizon in a dark sky just before the start of
morning twilight. At 71 km/sec. the Leonids produce mostly swift meteors
with a high percentage of persistent trains.

The Sporadic rates for the Northern Hemisphere are now at their high plateau
for the year. Observers can expect around ten random meteors per hour during
the morning hours as seen from locations in the Northern hemisphere. During
the dark evening hours perhaps three random meteors can be seen per hour
north of the equator. Sporadic rates seen from the Southern Hemisphere have
reached a minimum and will slowly rise during the remainder of the year.
>From south of the equator one would expect to see approximately five random
meteors per hour during the morning hours and two per hour during the
evening. Evening rates in both hemispheres are reduced due to moonlight.

Delta Eridanids (ERI)  03:44 (056) -02
Hourly Rate = N. Hemisphere <1 - S. Hemisphere <1

Anthelion    04:24 (066) +21
Hourly Rate = N. Hemisphere 3 - S. Hemisphere 2

Alpha Monocerotids (AMO)    03:56 (059) +02
Hourly Rate = N. Hemisphere <1 - S. Hemisphere <1

Zeta Puppids (ZPU)   07:48 (117) -42
Hourly Rate = N. Hemisphere <1 - S. Hemisphere 1

Leonids (LEO)    09:56 (149) +23
Hourly Rate = N. Hemisphere 1 - S. Hemisphere 1

Clear Skies!
Robert Lunsford
American Meteor Society