(meteorobs) Meteor Activity Outlook for November 14-20, 2009

[Robert Lunsford]

As seen from the northern hemisphere, meteor rates continue to be strong in
November. While no major showers are active this month, the two Taurid
radiants plus the Leonids keep the skies active. The addition of strong
sporadic rates make November one of the better months to view meteor
activity from north of the equator. Skies are fairly quiet as seen from the
southern hemisphere this month. Activity from the three showers mentioned
above may be seen from south of the equator, but the sporadic rates are much
lower than those seen in the northern hemisphere.

During this period the moon reaches its new phase on Monday November 16th.
On that date the moon lies close to the sun and is not visible at night. The
same circumstances exist for this weekend. As the week progresses the waxing
crescent moon will enter the evening sky but still set well before the
active morning hours arrive. 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 twenty-two from the northern hemisphere
and ten 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 November 14/15. 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:

Sirko Molau's studies of video radiants has revealed that activity from the
famous Andromedid shower, noted for intense storms during the 19th century,
may still be seen throughout November. The current position of the large
radiant is 01:33 (023) +33. This position lies near the intersection of the
constellations of Pisces, Triangulum, and Andromeda. The nearest bright star
is second magnitude Mirach (Beta Andromedae), which lies four degrees to the
northwest. Visual activity is expected to be low, but detectable. The
Andromedid radiant is best placed near 2200 (10pm) local standard time (LST)
when it lies on the meridian. At 19km/sec., the average Andromedid will
appear as a very slow moving meteor. Sirko mentions that these meteors are
"conspicuously slow and of almost constant activity" during this period.

Another shower verified by video means are the Omicron Eridanids (OER). This
shower is active from November 13-20 with maximum activity occurring on the
14th. The radiant is currently located at 04:02 (060) -02. This position
lies in eastern Eridanus, fifteen degrees northwest of zero magnitude Rigel
(Beta Orionis) and eight degrees south of fourth magnitude star Nu Tauri.
The radiant is best placed near 0100 LST, when it lies highest above the
horizon. Current rates would be less than one per hour. At 27km/sec., the
average Omicron Eridanid is slow.

The Northern Taurids (NTA) are active from a large radiant centered at 04:06
(061) +23, which lies in western Taurus, four degrees southeast of the
famous naked eye star cluster known as the Pleiades. The radiant is best
placed near 0100 LST, when it lies highest above the horizon, but activity
may be seen all night long. Meteors from the Northern Taurids strike the
atmosphere at 29km/sec., which would produce meteors of slow velocity.
Expected rates would be near three per hour as seen from the northern
hemisphere and two per hour as seen south of the equator.

The center of the large Southern Taurid (STA) radiant lies at 04:09 (062)
+15. This position lies in western Taurus, five degrees southwest of the
first magnitude orange star Aldebaran (Alpha Tauri). The radiant is best
placed near 0100 LST, when it lies highest above the horizon, but activity
may be seen all night long. Striking the atmosphere at 29 km/sec., the
average Southern Taurid meteor travels slowly through the skies. Rates
should be near one per hour no matter your location.

The November Orionids (NOO) were recently discovered by analyzing video
data. This shower is active from November 18 through December 9. Maximum
activity occurs on November 30. The radiant is currently (11/18) located at
05:32 (083) +16. This position lies on the Orion/Taurus border, six degrees
north of the third magnitude star Lambda Orionis. These meteors are also
best seen near 0300 LST when the radiant lies on the meridian and highest
above the horizon. At 44 km/sec. the November Orionids produce mostly medium
velocity meteors.

The Alpha Monocerotids (AMO) are active from November 15-25, with maximum
occurring on the 21st. This shower has produced outbursts in the past but
none are expected for many years to come. Rates are expected to be less than
one shower member per hour, even on the night of maximum activity. The
radiant is currently located at 07:28 (112) +02. This position lies in
central Canis Minor, only three degrees southwest of the zero magnitude star
Procyon (Alpha Canis Minoris). These meteors are also best seen near 0500
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) reach maximum activity on the morning of November 17th.
The Leonids possess a sharp peak of short duration. These peaks in activity
are caused by the Earth passing close to one of the filaments of material
produced by comet 55P Temple-Tuttle. This year the Earth passes close to the
several filaments. Between 2100 and 2200 Universal Time (UT) on November
17th, the Earth is expected to pass through three filaments that were
produced by 55P Temple-Tuttle in 1466 and 1533. This timing is best for
those watching from central Asia. A fairly strong traditional maximum is
also expected near 0900 UT, which is well timed for North America. This
corresponds to 0400 EST, 0300 CST, 0200 MST, and 0100 PST on the morning of
the 17th. The radiant is currently located at 10:09 (152) +23. This position
lies in western Leo, just west of the third magnitude star Zeta Leonis.
Rates this weekend are expected to be near one per hour. At 70km/sec., the
average Leonid is swift with a high percentage of trains. The radiant does
not rise until the late evening hours so it is advised to wait until after
midnight before beginning serious observations. The radiant is most
favorably located during the last dark hour before the onset of morning
twilight when it lies highest in a dark sky.

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 four
per hour. As seen from the mid-southern hemisphere (45S), morning rates
would be near six 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.

Andromedids (AND)   - 01:33 (023) +33  Velocity - 19km/sec.
Northern Hemisphere -<1 per hr. Southern Hemisphere - <1 per hr.

Omicron Eridanids (OER)   - 04:02 (060) -02  Velocity - 27km/sec.
Northern Hemisphere -<1 per hr. Southern Hemisphere - <1 per hr.

Northern Taurids (NTA)   - 04:06 (061) +23  Velocity - 29km/sec.
Northern Hemisphere - 3 per hr. Southern Hemisphere - 2 per hr.

Southern Taurids (STA)  - 04:09 (062)+15   Velocity - 29km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr.

November Orionids (NOO) - 05:32 (083) +16   Velocity - 44km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Alpha Monocerotids (AMO)  - 07:28 (112) +02   Velocity - 65km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Leonids (LEO)  - 10:09 (152) +23   Velocity - 70km/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