(meteorobs) Meteor Activity Outlook for December 1-7, 2006

[Robert Lunsford]

December is the last month of strong activity as seen in the northern
hemisphere. During the first half of the month minor showers are active in
the constellations of Taurus (Antihelions), Monoceros (Monocerotids), Puppis
(Puppid-Velids), Hydra (Sigma Hydrids), and Leo (Coma Berenicids). Strong
sporadic rates continue during the morning hours as long as the moon is
below the horizon. Rates increase significantly with the arrival of the
Geminids during the second week of the month. From the southern hemisphere,
sporadic rates are increasing in strength toward a peak in January. Meteors
from the above minor showers are also well seen from south of the equator.
The Geminids also increase the southern activity, but not nearly to the
extent that is witnessed in the northern hemisphere.

This week the moon reaches its full phase on Tuesday December 5. At this
time the moon will be present in the sky during the entire night, spoiling
the view of meteor activity. This weekend the moon will set an hour or two
before dawn so there is a small window of opportunity to view under dark
skies. The estimated total hourly rates for evening observers this week is
near three for those north of the equator and two for observers south of the
equator. For morning observers the estimated total hourly rates should be
near twelve for northern observers and ten for those south of the equator.
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. Rates are reduced due
to intense moonlight this week.

The radiant positions listed below are exact for Saturday night/Sunday
morning December 2/3. 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. This method 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.

These showers are expected to be active this week:

The Phoenicids (PHO) is a periodic shower that rarely produces activity. The
only impressive display produced by this shower occurred in 1956 when ZHR's
were near 100. Peak activity occurs on December 6. Little activity is
expected away from the peak night. The radiant is located at 01:08
(017) -53. This position lies in southeastern Phoenix some 5 degrees
northwest of the bright zero magnitude star Achernar (Alpha Eridani). These
meteors are best seen near 2100 (9pm) local standard time (LST) when the
radiant lies highest above the horizon in a dark sky. Due to the southerly
declination, this shower is not visible north of the Northern Tropical
areas. The deep Southern Hemisphere has the best chance of seeing any
activity. At 22 km/sec. the Phoenicids produce very slow meteors.

The Antihelion (ANT) radiant is now centered at 05:32 (083) +23. This area
of the sky lies in eastern Taurus, six degrees southeast of the second
magnitude star El Nath (Beta Tauri). This radiant is best placed near 0100
LST when it lies on the meridian and is highest in the sky. Rates at this
time should be near two per hour as seen from the northern hemisphere and
one per hour for observers located south of the equator. With an entry
velocity of 30 km/sec., the average Antihelion meteor would be of
medium-slow speed.

The Monocerotids (MON) are currently active from a radiant located at 06:16
(094) +08. This area of the sky is located in eastern Orion, four degrees
east of the 1st magnitude star Betelgeuse (Alpha Orionis). These meteors are
best seen near 0100 local standard time when the radiant lies highest above
the horizon. The peak for the Monocerotids occurs on December 8 when the ZHR
reaches 3. This shower would be equally well seen from both hemispheres. At
42 km/sec. the Monocerotids produce meteors of average velocity.

The Puppid-Velids (PUP) is 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
08:16 (124) -45. This position lies in western Vela, three degrees north of
the second magnitude star Gamma Velorum. These meteors are best seen near
0300 LST 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 40 km/sec. the Puppid-Velids produce meteors of average
velocity.

Sporadic rates have reached the late year plateau for observers located in
the northern hemisphere. One would expect to see perhaps eight random
meteors during the last hour before dawn from rural observing sites. During
the first dark hour after the end of evening twilight, perhaps three random
meteors can be seen per hour. Sporadic rates increase as the night
progresses so rates seen near midnight would be near six per hour. Sporadic
rates seen from the southern hemisphere have passed their annual minimum and
are rising again. One would expect to see approximately four random meteors
per hour during the last hour before dawn and two per hour during the first
dark hour after the end of evening twilight. Rates near midnight would be
near three per hour. Rates are reduced due to intense moonlight this week.

Phoenicids (PHO) 01:08 (017) -53
Northern Hemisphere - 0   Southern Hemisphere - >1

 Antihelion (ANT) - 05:32 (083) +23
Northern Hemisphere - 2   Southern Hemisphere - 1

Monocerotids (MON)  06:16 (094) +08
Northern Hemisphere - 1   Southern Hemisphere - 1

Puppid-Velids (PUP)  8:16 (124) -45
Northern Hemisphere - 1   Southern Hemisphere - 3

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2006

Clear Skies!
Robert Lunsford
American Meteor Society