(meteorobs) Meteor Activity Outlook for January 7-13, 2005

[Robert Lunsford]

This upcoming period will see the moon reaching its new phase on Monday
January 10.  During this entire period the moon will be close to the sun and
will not interfere with any meteor observing. This will be the best time of
the month to try and view meteor activity. The estimated total hourly rates
for evening observers this week should be near three for those in the
Northern Hemisphere and four for those observers south of the equator. For
morning observers the estimated total hourly rates should be near thirteen
for those located in the Northern Hemisphere and fifteen 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.

The radiant positions listed below are exact for Saturday night/Sunday
morning January 8/9. 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 08:12 (123) +19. This area of the
sky is located in western Cancer, ten degrees southeast of the first
magnitude star Pollux (Beta Geminorum). Since this radiant is large and
diffuse, any slow to medium speed meteor from northern Canis Minor, eastern
Gemini, northwestern Hydra or Cancer 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
two shower members per hour from the Northern Hemisphere and one per hour
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. 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. Observers who send their reports to the
International Meteor Organization (I.M.O.) should label these meteors as
Delta Cancrids (DCA).

The Gamma Velids (GVE) are the first of many weak southern showers active
during January and February. The Gamma Velids are listed among the radiants
of the Dutch Meteor Society and reached maximum activity on January 5.
Current rates would be low, most likely less than one shower member per
hour. The radiant is currently located near 08:32 (128) -48. This position
lies in western Vela, three degrees east of the second magnitude star Gamma
Velorum.  The radiant lies highest in the sky between 0100 and 0200. This
shower is not visible north of latitude 45 north. At 35 km/sec. the Gamma
Velids produce meteors of average velocity.

The Alpha Hydrids (AHY) is another shower listed among radiants of the Dutch
Meteor Society. The date of maximum activity is January 13 with a predicted
ZHR of two. Current rates would be most likely less than one shower member
per hour. With such low activity care must be taken to exclude any sporadic
activity from the Alpha Hydrid count. The radiant currently lies at 08:40
(130) -10. This position lies in western Hydra twelve degrees southwest of
the second magnitude star Alphard (Alpha Hydrae). This radiant is seen
equally well from both hemispheres. The area of the sky is also best placed
near  0200 local standard time. At 44 km/sec. the Alpha Hydrids produce
meteors of  average velocity.

The Alpha Crucids (ACR) is yet another shower listed among the radiants of
the Dutch Meteor Society. The date of maximum activity is January 14 with a
predicted ZHR of three. Like the previous weak showers, care must be taken
to exclude any sporadic activity from the Alpha Crucid count. The radiant
currently lies at 12:24 (186) -61. This position lies in extreme
southwestern Centaurus, three degrees north of the third magnitude star
Lambda Centauri. Due to the far southern declination this shower is not well
seen north of the northern equatorial regions. The area of the sky is also
best placed just before dawn when it lies highest in the sky. At 50 km/sec.
the Alpha Crucids produce meteors of medium swift velocity.

The Coma Berenicids (COM) are active from a radiant located at 12:56 (194)
+17. This area of the sky lies in southern Coma Berenices, six degrees
northwest of the third magnitude star Vindemiatrix (Epsilon Virginis). This
radiant is best placed for viewing just before dawn, when it lies highest
above the horizon. The predicted date of maximum activity was December 19,
when the predicted ZHR reached five. Current rates are most likely less than
one per hour. At 65 km/sec. the Coma Berenicids produce mostly swift meteors
with the brighter shower members leaving persistent trains.

The Sporadic rates for the Northern Hemisphere are now just past their
annual peak. One would expect to see perhaps ten random meteors per hour
during the last hours before dawn from rural observing sites. During the
evening hours perhaps three random meteors can be seen per hour. Sporadic
rates seen from the Southern Hemisphere are increasing toward a peak this
month. One would see approximately twelve random meteors per hour during the
late morning hours and four per hour during the evening.

Anthelion        Radiant Position  = 08:12  (123) +19
Hourly Rate = 3  N. Hemisphere, 2  S. Hemisphere

Gamma Velids (GVE)   Radiant Position  = 08:32 (128)  -48
Hourly Rate = 0  N. Hemisphere, <1  S. Hemisphere

Alpha Hydrids (AHY)   Radiant Position  = 08:40 (130)  -10
Hourly Rate = <1  N. Hemisphere, <1  S. Hemisphere

Alpha Crucids (ACR)   Radiant Position  = 12:24 (128)  -61
Hourly Rate = 0  N. Hemisphere, 1  S. Hemisphere

Coma Berenicid (COM)   Radiant Position  = 12:56 (191)  +17
Hourly Rate = <1  N. Hemisphere, <1  S. Hemisphere

Clear Skies!
Robert Lunsford
American Meteor Society