(meteorobs) Meteor Activity Outlook for December 12-18, 2009

[Robert Lunsford]

No matter where you live, the first half of December provides some of the best meteor activity of the year. In the northern
hemisphere the sporadic rates are still strong plus you can also count on strong activity from the Geminids, which peak on December
13. There are also several minor radiants that add a few meteors each hour. All of these centers of activity are located high in the
sky during the early morning hours this time of year. Unfortunately this year the bright moon spoils the show during the first week
of the month. During the second week of December the moon will pass its last quarter phase and will not be such a nuisance .

As seen from the southern hemisphere the sporadic rates are increasing toward a January maximum. Shower rates are also good but the
Geminids suffer a bit from the lower elevation seen from southern locations. Still with the warmer weather now occurring south of
the equator, December is a great time to view celestial fireworks.

During this period the moon reaches its new phase on Wednesday December 16th. On that date the moon lies near the sun and cannot be
seen at night. This weekend the waning crescent moon will rise during the late morning hours but will not cause any interference.
The estimated total hourly rates for evening observers this week is near five as seen from the northern hemisphere and three from
the southern hemisphere. For morning observers the estimated total hourly rates should be near forty from the northern hemisphere
and twenty as seen from the southern hemisphere. 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 and rates listed below are exact for Saturday night/Sunday morning December 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. It must be remembered that meteor activity is rarely seen at the radiant
position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the
edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower
member) or in another direction if it is a sporadic. 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.

The following showers are expected to be active this week:

Now that the activity from particles produced by comet 2P/Encke has ceased encountering the Earth, the Taurid showers for 2009 are
over and we resume reporting activity from the Antihelion radiant. This is not a true radiant but rather activity caused by the
Earth's motion through space. As the Earth revolves around the sun it encounters particles orbiting in a pro-grade motion that are
approaching their perihelion point. They all appear to be radiating from an area near the opposition point of the sun, hence the
name Antihelion. These were once recorded as separate showers throughout the year but it is now suggested to bin them into their
category separate from true showers and sporadics. This radiant is a very large oval some thirty degrees wide by fifteen degrees
high. Activity from this radiant can appear from more than one constellation. The position listed here is for the center of the
radiant which is currently located at 06:16 (094) +23. This position lies in western Gemini near the fourth magnitude star Eta
Geminorum. Antihelion activity may also appear from eastern Taurus, northeastern Orion, or southern Auriga. This radiant is best
placed near 0100 local standard time (LST) when it lies on the meridian and is highest in the sky. Rates at this time should be near
three per hour as seen from the northern hemisphere and two per hour from south of the equator. With an entry velocity of 30
km/sec., the average Antihelion meteor would be of slow speed.

The Monocerotids (MON) are active from a radiant located at 06:52 (103) +07. This position lies in northwestern Monoceros halfway
between the bright stars Betelgeuse (Alpha Orionis) and Procyon (Alpha Canis Minoris). This shower peaked on December 8, so activity
is waning. Current rates would most likely average less than one per hour no matter your location. The Monocerotids are best seen
near 0100 LST when the radiant lies highest above the horizon. At 41 km/sec. the Monocerotids produce mostly meteors of medium
velocity.

The Geminids (GEM) are active from a radiant located at 07:33 (113) +32. This position lies in northern Gemini near the fourth
magnitude star Rho Geminorum. Although Geminid meteors can be seen all night long, they are best seen near 0200 LST when the radiant
lies highest above the horizon. This shower is expected to peak Sunday and Monday December 13/14 when rates can surpass 60 shower
members per hour as seen from dark sites. Geminid activity can be seen from the southern hemisphere but at at much reduced rate. As
seen from south of the equator, Geminid activity could only be seen for a few hours before and after 0200 LST. At 35 km/sec. the
Geminids produce mostly meteors of medium velocity.

The Puppid-Velids (PUP) are a vast complex of weak radiants located in the constellations of Puppis and Vela. Visual plots and
photographic studies have revealed many radiants in this area during November and December. The combined strength of these radiants
can produce a ZHR of ten. Actual hourly rates will be much less unless you happen to be observing from the deep Southern Hemisphere.
The center of this activity is currently located at 08:26 (126) -45. This position lies in western Vela, five degrees northeast of
the second magnitude star Gamma Velorum. Peak rates occurred near December 7 so current activity is waning. These meteors are best
seen near 0300 LST when the radiant lies highest above the horizon. 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 40 km/sec. the
Puppid-Velids produce meteors of medium velocity.

The Sigma Hydrids (HYD) are active from a radiant located at 08:42 (130) +01. This position lies in western Hydra, just below the
group of fourth magnitude stars that make up the "head" of the water serpent. These meteors are best seen near 0300 LST when the
radiant lies highest above the horizon. Current rates would be near one per hour no matter your location. At 61 km/sec. the Sigma
Hydrids produce mostly swift meteors.

The December Leonis Minorids (DLM) are active from a radiant located at 10:22 (155) +34. This position lies in central Leo Minor,
approximately ten degrees north of the third magnitude star Zeta Leonis. These meteors are best seen near 0500 LST when the radiant
lies highest above the horizon. This shower peaks on December 20th so current rates would be near one per hour as seen from the
northern hemisphere and less than one per hour as seen from south of the equator. At 64 km/sec. the December Leonis Minorids produce
mostly swift meteors.

Activity from the Coma Berenicids (COM) has just begun for 2009. The radiant is located at 11:30 (173) +18. This position actually
lies in eastern Leo, five degrees northwest of the second magnitude star Denebola (Beta Leonis). These meteors are best seen near
0600 LST when the radiant lies highest above the horizon. This shower peaks on December 16th so current rates would be near one per
hour no matter your location. At 65 km/sec. the Coma Berenicids produce mostly swift meteors.

Lastly, the December Alpha Draconids (DAD) are active from a radiant located at 14:00 (210) +58. This position actually lies in
northeastern Ursa Major, six degrees northeast of the second magnitude double star Mizar (Zeta Ursae Majoris). These meteors are
best seen during the last dark hour before dawn, when the radiant lies highest above the horizon in a dark sky. This shower is near
the end of its activity period so expected rates would be less than one no matter your location. At 44 km/sec. the Alpha Draconids
produce mostly medium speed meteors.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately sixteen Sporadic meteors per hour during the
last hour before dawn as seen from rural observing sites. Evening rates would be near three per hour. As seen from the mid-southern
hemisphere (45S), morning rates would be near ten per hour as seen from rural observing sites and two per hour during the evening
hours. Locations between these two extremes would see activity between the listed figures.

The table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday
night/Sunday morning but may be used all week long.

Antihelion (ANT)) - 06:16 (094) +23   Velocity - 30km/sec.
Northern Hemisphere - 3 per hr. Southern Hemisphere - 2 per hr.

Monocerotids (MON) - 06:52 (103) +07   Velocity - 41km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Geminids (GEM) - 07:33 (113) +32   Velocity - 35km/sec.
Northern Hemisphere - 60 per hr. Southern Hemisphere - 20 per hr.

Puppid-Velids (PUP) - 08:26 (126) -45   Velocity - 40km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - 2 per hr.

Sigma Hydrids (HYD) - 08:42 (130) +01   Velocity - 61km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr.

December Leonis Minorids (DLE) - 10:22 (155) +34   Velocity - 64km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - <1 per hr.

Coma Berenicids (COM)) - 11:30 (173) +18   Velocity - 65km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr.

Alpha Draconids (DAD) - 14:00 (210) +58   Velocity - 44km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2009

Clear Skies!
Robert Lunsford
American Meteor Society