(meteorobs) Meteor Activity Outlook for November 30-December 6, 2007

[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 14. 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.
The night of December 13/14 is no doubt the best night of the year to view
meteor activity. The moon is favorable during this entire period. After the
15th, the shower activity suddenly wanes and a great majority of the
activity seen is sporadic. Approaching Christmas the moon become a major
factor and ruins the maximum of the Ursid shower.

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 Saturday
December 1. At this time the moon will be located ninety degrees west of the
sun and will rise near midnight local standard time. As the week progresses
the moon will rise later in the morning and will become less of a nuisance
as it approaches its new phase. The estimated total hourly rates for evening
observers this week is near four for those located in the mid-northern
hemisphere (45 N) and two for observers from the mid-southern hemisphere (45
S). For morning observers the estimated total hourly rates should be near
sixteen for those located in the mid-northern hemisphere (45 N) and ten for
those viewing from the mid-southern hemisphere (45 S). 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. Morning rates are reduced due to
moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning December 1/2. 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:

The Phoenicids (PHO) are a periodic shower that rarely produces noticeable
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 currently
located at 01:04 (016) -53. This position lies in southeastern Phoenix some
6 degrees northwest of the bright zero magnitude star Achernar (Alpha
Eridani). These meteors are best seen near 2100 (9pm) local standard time
(LST, regardless of time zone)when the radiant lies highest above the
horizon in a dark sky. Due to the southerly declination of the radiant, 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 Earth has now passed the stream of particles produced by comet 2P/Encke,
which gives us the Taurid meteors each autumn. As we enter the month of
December we again recognize the ever present Antihelion (ANT) radiant. This
large, diffuse radiant is now centered at 05:28 (082) +23. This position
lies in eastern Taurus, six degrees south of the second magnitude star El
Nath (Beta Tauri). This area of the sky is best placed on the meridian near
0100 local standard time (LST). One can expect to see approximately three
shower members per hour as seen from the northern hemisphere and two per
hour from south of the equator. At 30km/sec., the average Antihelion meteor
travels slowly through the skies.

The Monocerotids (MON) are currently active from a radiant located at 06:12
(093) +08. This area of the sky is located in eastern Orion, three degrees
east of the 1st magnitude star Betelgeuse (Alpha Orionis). These meteors are
best seen near 0100 LST when the radiant lies highest above the horizon. The
peak for the Monocerotids is published as December 8 but recent video
studies by Sirko Molau shows a week-long peak of weak activity commencing on
December 6 and ending rather suddenly on the 16th. This shower would be
equally well seen from both hemispheres. Current rates are most likely near
one per hour. At 42 km/sec. the Monocerotids produce meteors of average
velocity.

Video data has also shown that activity from northern Orion begin appearing
on November 17 from a radiant located at 6:16 (094) +16. This position lies
eight degrees northeast of the first magnitude orange star Betelgeuse (Alpha
Orionis). Current rates would be low, most likely less than one per hour.
These meteors are best seen near 0200 LST when the radiant culminates on the
meridian. Maximum activity occurred on the 28th. At 42 km/sec. the November
Orionids (NOO) produce meteors of average velocity. Be careful as the
Monocerotid radiant lies only eight degrees north of this radiant. If both
radiants are not visible in your field of view then separating these two
showers is nearly impossible. This shower was recently listed at the Lambda
Orionids but it appears that this activity is identical with IAU shower
#250, the November Orionids.

Low activity from the Sigma Hydrids (HYD) may be seen from a radiant located
at 08:00 (120) +04. This area of the sky is located in eastern Canis Minor,
five degrees east of the zero magnitude star Procyon (Alpha Canis Minoris).
These meteors are best seen near 0300 local standard time when the radiant
lies highest above the horizon. The predicted peak for the Sigma Hydrids
occurs on December 12 when the ZHR reaches two. Recent studies have
indicated that this shower may peak earlier in the month so careful
monitoring this week of any activity would be valuable. Current rates are
expected to be less than one shower member per hour. At 58 km/sec. the Sigma
Hydrids produce meteors of average to swift 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
08:12 (123) -45. This position lies in western Vela, three degrees north of
the second magnitude star Gamma Velorum. Peak rates occur near December 7.
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 maximum for observers in the northern hemisphere
and are now slowly rising for those located south of the equator. One would
expect to see approximately twelve random meteors during the last hour
before dawn from rural observing sites in the mid-northern hemisphere (45
N). During the first dark hour after the end of evening twilight, perhaps
four random meteors can be seen per hour. As seen from the mid-southern
hemisphere (45 S) late morning rates would now be near six per hour. During
the first dark hour after the end of evening twilight, perhaps two random
meteors can be seen per hour. Moonlight interferes with morning rates during
this period.

Phoenicids (PHO)  01:04 (016) -53
Northern Hemisphere - <1   Southern Hemisphere - <1

Antihelion (ANT) - 05:28 (082) +23
Northern Hemisphere - 3   Southern Hemisphere - 2

Monocerotids (MON)  06:12 (093) +08
Northern Hemisphere - 1   Southern Hemisphere - 1

November Orionids (NOO)  06:16 (094) +16
Northern Hemisphere - <1   Southern Hemisphere - <1

Sigma Hydrids (HYD)  08:00 (120) +04
Northern Hemisphere - <1   Southern Hemisphere - <1

Puppid-Velids (PUP)  08:12 (123) -45
Northern Hemisphere - <1   Southern Hemisphere - 1

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#2007

Clear Skies!
Robert Lunsford
American Meteor Society