(meteorobs) Meteor Activity Outlook for October 28- November 3, 2005

[Robert Lunsford]

The moon reaches its new phase on Wednesday November 2nd. At this time the
moon will rise and set with the sun and will not interfere at all with
observing at any time of the night. This weekend a waning crescent moon will
not cause any interference and it will be quite slender and will also rise
late in the morning. The estimated total hourly rates for evening observers
this week should be near five for Northern Hemisphere observers and three
for those located in the Southern Hemisphere. For morning observers the
estimated total hourly rates should be near fourteen for Northern Hemisphere
observers and eight 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.

The radiant positions listed below are exact for Saturday night/Sunday
morning October 29/30. 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 Anthelion radiant is now centered at 03:28 (052) +19. This area of the
sky is located on the Aries/Taurus border, seven degrees southwest of the
Pleiades (Seven Sisters) open star cluster. Since this radiant is large and
diffuse, any slow to medium speed meteor from Aries, northeastern Cetus, or
western Taurus could be a candidate for this shower. The center of this area
is best placed near 0200 local daylight 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 four per hour
from the Northern Hemisphere and three 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.

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 Orionids (ORI) reached maximum activity on October 21, but at still
active from a radiant located at 06:44 (101) +16. This position lies in
southwestern Gemini, only one degree east of the second magnitude star
Alhena (Gamma Geminorum). The radiant is best placed near 0400 when it is
located near the meridian and lies highest above the horizon. Current rates
would be near one shower member per hour. At 66km/sec., the average Orionid
is swift and bright shower members tend to leave persistent trains.

The Sporadic rates for the Northern Hemisphere are now at their high plateau
for the year. Observers can expect around twelve random meteors per hour
during the morning hours as seen from locations in the Northern hemisphere.
During the dark evening hours perhaps four 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 six
random meteors per hour during the morning hours and two per hour during the
evening.

Anthelion    03:28 (052) +19
Hourly Rate = N. Hemisphere 4 - S. Hemisphere 3

Orionids (ORI)   06:44 (101) +16
Hourly Rate = N. Hemisphere 1 - S. Hemisphere 1

Clear Skies!
Robert Lunsford
American Meteor Society