(meteorobs) Meteor Activity Outlook for January 6-12, 2006

[Robert Lunsford]

In this edition of the meteor activity outlook you will notice an additional
column in the meteor shower table. I have added meteor shower
classifications to help the observer target potential activity for an
observing session. The classifications are simple; Class I is a strong
display with a ZHR of at least ten at maximum activity. Class II covers
minor showers with ZHR's of at least three at maximum activity. Class III
covers those showers with widely variable rates such as the Leonids and June
Bootids. Class IV includes all other showers with weak activity not easily
classified by visual observers. Since a majority of the readers are strictly
visual observers, I have often been tempted to remove class IV showers from
discussion as these showers are better targets for photographic and video
observers.  On the other hand, removing these weak showers would be a
disservice to those observers who actually use cameras and video recorders
to study such obscure activity. My fear is that inexperienced observers may
report sporadic activity as being associated with these showers, giving the
illusion that these showers are far more active than they really are. It is
satisfying to know that during the several years these showers have been
included, no obvious observations of enhanced rates have been noted. This
leads me to believe that the readers are indeed careful when it comes to the
classification of meteor activity. So for now, I will still include the
class IV showers with a warning that these showers are visually difficult to
separate from the sporadic background.

The moon reaches its first quarter phase on Friday January 6. At this time
the moon will set near midnight local standard time, allowing the remainder
of the night to be free of interfering moonlight. Later in this period, the
waxing gibbous moon will be in the sky most of the night allowing only a
small opportunity of viewing in dark skies between the time of moon set and
the start of morning twilight. The estimated total hourly rates for evening
observers this week should be near four for Northern Hemisphere observers
and three for those located in the Southern Hemisphere. For morning
observers the estimated total hourly rates should be near thirteen 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.  Evening
rates in both hemispheres are reduced due to moonlight.

The radiant positions listed below are exact for Saturday night/Sunday
morning January 7/8. 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 Eclipticid (ECL) radiant is now centered at 07:56 (119) +21. This area
of the sky is located in eastern Gemini, seven degrees south of the first
magnitude star Pollux (Beta Geminorum). This radiant is best placed near
0100 local standard time when it lies on the meridian and is highest in the
sky. Rates should be near two per hour from the Northern Hemisphere and one
per hour for observers south of the equator. With an entry velocity of 28
km/sec., the average Eclipticid meteor would be of medium-slow speed. This
radiant is a good source of fireballs, more so as we progress through the
winter months. Those who send reports to the I.M.O. should label these
meteors as Delta Cancrids (DCA).

The Gamma Velids (GVE) are a class IV shower (best left for study by
observers who use video and photographic observations). This is 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. Visual rates would be low, most likely less
than one shower member per hour. The radiant is currently located near 08:28
(127) -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 class IV shower listed among radiants of
the Dutch Meteor Society. The date of maximum activity is January 14 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 08:32 (128) -10. This position lies in western Hydra, fourteen
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 on the meridian near 0200 local standard time. At 44
km/sec. the Alpha Hydrids produce meteors of average velocity.

The Alpha Crucids (ACR) is yet another class IV shower listed among the
radiants of the Dutch Meteor Society. The date of maximum activity is
January 15 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 12:12 (183) -59. This position lies in
western Crux, only one degree west of the third magnitude star Delta Crucis.
Due to the far southern declination this shower is not 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) reached maximum activity on December 19,
when the ZHR reached five. Current rates would be 1-2 shower members
per hour at best. The radiant is currently located at 12:52 (193) +17, which
places it in southern Coma Berenicids, four degrees west of the fourth
magnitude star Alpha Comae Berenices. This radiant is best placed for
viewing just before dawn, when it lies highest above the horizon. 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 eight random meteors per hour
during the last hours before dawn from rural observing sites. During the
evening hours perhaps two 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 six random meteors per hour during the
late morning hours and one per hour during the evening. Evening rates in
both hemispheres are reduced due to moonlight.

Eclipticid     07:56 (119) +21   Class II
Hourly Rate = N. Hemisphere 2 - S. Hemisphere 1

Gamma Velids (GVE)   08:28 (127) -48   Class IV
Hourly Rate = N. Hemisphere 0 - S. Hemisphere >1

Alpha Hydrids (AHY)   08:32 (128) -10   Class IV
Hourly Rate = N. Hemisphere 1 - S. Hemisphere 1

Alpha Crucids (ACR)   12:12 (183) -59   Class IV
Hourly Rate = N. Hemisphere >1 - S. Hemisphere 1

Coma Berenicids (COM)   12:52 (193) +17   Class II
Hourly Rate = N. Hemisphere 2 - S. Hemisphere 1

Clear Skies!
Robert Lunsford
American Meteor Society