(meteorobs) Meteor Activity Outlook for December 13-19, 2008

[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.

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 last quarter phase on Friday
December 19th. At this time the moon will rise near midnight local standard
time (LST) and will be in the sky the remainder of the morning. This weekend
and next week the waning gibbous moon will be in the sky most of the night
making it difficult to observe any activity. The estimated total hourly
rates for evening observers this week is near five for those located in the
mid-northern hemisphere (45 N) and three for those viewing from the
mid-southern hemisphere (45 S). For morning observers the estimated total
hourly rates should be near twenty five for those located in the
mid-northern hemisphere (45 N) and ten for those viewing from the
mid-southern hemisphere (45 S). Locations between these two extremes would
see activity between the listed figures. 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 the bright moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning December 13/14. 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 full descriptions of each active meteor shower will continue next week
when the moon becomes less of a nuisance to observers.

The following showers are expected to be active this week:

Antihelion (ANT) - 06:20 (095) +23
Monocerotids (MON)  06:32 (104) +08
Geminids (GEM)  07:28 (112) +33
Puppid-Velids (PUP)  08:32 (128) -45
Sigma Hydrids (HYD)  08:40 (130) +01
Coma Berenicids (COM)  10:28 (157) +33
Chi Virginids (CVR)  12:40 (190) -10

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2008

Clear Skies!
Robert Lunsford
American Meteor Society