(meteorobs) Meteor Activity Outlook for November 17-23, 2006

[Robert Lunsford]

Meteor rates continue to be strong as seen from the northern hemisphere. The
antihelion radiant has merged with the two Taurid radiants producing slow
meteors that are visible during the evening and early morning hours. Swift
meteors from the Leonid radiant can be seen during the morning hours for two
weeks centered at mid-month. Strong sporadic rates continue during the
morning hours as long as the moon is below the horizon. From the southern
hemisphere, sporadic rates are increasing in strength toward a peak in
January. Meteors from the Leonid and Taurid radiants also help to fill the
southern skies with more activity. A new moon during the peak of the Leonid
shower will help provide observers with dark skies.

This week the moon reaches its new phase on Monday November 20. At this time
the moon will lie close to the sun in the sky and will not be visible at
night. This will be the best time of the month to view meteor activity. The
estimated total hourly rates for evening observers this week is near five
for those north of the equator and three for observers south of the equator.
For morning observers the estimated total hourly rates should be near twenty
five for northern observers and fifteen 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.

The radiant positions listed below are exact for Saturday night/Sunday
morning November 18/19. 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. Doing this 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:

At this time of year debris from comet 2P/Encke produces a double radiant
very close to the position of the antihelion radiant. From now through the
end of November, it is impossible to resolve the antihelion meteors from
those produced by comet 2P/Encke. Therefore we suggest that observers simply
classify meteors from this area as either north or south Taurids.

The Northern Taurid (NTA) radiant is now centered at 04:20 (065) +24. This
position lies in northern Taurus, eight degrees east of the Pleiades star
cluster. The Southern Taurid (STA) radiant lies at 04:16 (064) +16. This
position lies in central Taurus, four degrees west of the first magnitude
star Aldebaran (Alpha Tauri). The two radiants are separated by eight
degrees. Since they have the same right ascension (celestial longitude), it
is difficult to distinguish meteors that move north or south out of the
radiants. It is slightly less difficult to distinguish those meteors
traveling east or west.

These radiants are above the horizon most of the night and are best placed
near midnight LST, when they lie on the meridian and are located highest in
the sky. Rates at this time should be near two per hour for the southern
radiant and three per hour for the northern radiant, regardless of your
location. With an entry velocity near 30 km/sec., the average Taurid meteor
would be of medium-slow speed.

Sirko Molau's study of video radiants has revealed activity during the
period November 17-December 5, from an area in northeastern Orion. Maximum
activity occurs on November 28 with the radiant located at 06:04 (091) +15.
This position lies one degree northwest of the fourth magnitude star Nu
Orionis. This radiant is best placed on the meridian near 0200 LST. It
appears that twelve percent of the total activity for the 28th is related to
this radiant. At 44km/sec., the average meteor from this radiant would be of
medium velocity. This activity has parameters quite similar to the
Monocertoids, but is a different shower as the video study also verified the
Monocerotids with its later activity period and more southerly radiant.

The Alpha Monocerotids (AMO) reach maximum activity on November 21 with
normally low rates of one or two shower members per hour. This shower has
produced outbursts in the past but none are expected for many years to come.
The radiant is located at 07:44 (116) +01. This position lies in
southeastern Canis Minor, three degrees southeast of the zero magnitude star
Procyon (Alpha Canis Minoris). These meteors are best seen near 0300 LST
when the radiant lies highest above the horizon in a dark sky. At 65 km/sec.
the Alpha Monocerotids produce mostly swift meteors.

The Leonids (LEO) will be best seen from November 17 through the 19th. The
Earth passes closest to the node of comet Temple-Tuttle late on the 17th
(Universal Time). The best chance for enhanced activity will most likely be
near 0445 UT on the 19th. This timing favors Western Europe and northwestern
Africa. From the western hemisphere, northeastern South America and eastern
North America may see enhanced activity as the radiant rises in the east on
Saturday evening/Sunday morning November 18/19. No one knows exactly the
strength of this peak. Optimistic forecasters are predicting rates of 2-3
Leonids per minute for a short time centered on the peak. Unfortunately
these Leonids will most likely be faint so those viewing from urban sites
will not be able to see much at all. Other locations than those mentioned
above should watch for activity late in the morning while the radiant is
high on the dates mentioned above. The radiant is located at 10:12 (153)
+22. This position lies in northwestern Leo, just one degree southwest of
the third magnitude star Aldhafera (Zeta Leonis). The radiant rises near
2300 (11:00pm) LST and is best placed in a dark sky just before the onset of
morning twilight. At 71km/sec., the average Leonid is swift.

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

Northern Taurid (NTA)  04:20 (065) +24
Northern Hemisphere - 3   Southern Hemisphere - 3

Southern Taurid (STA)  04:16 (064) +16
Northern Hemisphere - 2   Southern Hemisphere - 2

Nu Orionids (NOR)  06:04 (091) +15
Northern Hemisphere - 2   Southern Hemisphere - 2

Alpha Monocerotids (AMO)  07:44 (116) +01
Northern Hemisphere - 1   Southern Hemisphere - 1

Leonids (LEO)  10:12 (153) +22
Northern Hemisphere - 15   Southern Hemisphere - 10

*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