(meteorobs) Meteor Activity Outlook for October 24-30, 2009

[Robert Lunsford]

Meteor activity in general increases in October when compared to September.
A major shower (the Orionids) is active most of the month along with several
minor showers. Both branches of the Taurids become more active as the month
progresses, providing slow, graceful meteors to the nighttime scene. The
Orionids are the big story of the month reaching maximum activity on the
22nd. This display can be seen equally well from both hemispheres which
definitely helps out observers located in the sporadic-poor southern
hemisphere this time of year.

During this period the moon reaches its first quarter phase on Monday
October 26th. On that date the moon lies ninety degrees east of the sun and
sets near 0100 local daylight time (LDT), depending on your location. As the
week progresses the waxing gibbous moon sets later in the morning, lessening
the window of opportunity to view meteor activity in a dark sky. The
estimated total hourly rates for evening observers this week is near five as
seen from the northern hemisphere and two from the southern hemisphere. For
morning observers the estimated total hourly rates should be near twenty
five from the northern hemisphere and fifteen 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. Evening rates are reduced by
moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning October 24/25. 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.

A new radiant has been discovered in Ursa Minor which is active during this
period. The October Ursa Minorids (OUI) are active from October 16-28, with
maximum occurring on the 24th. The current radiant position lies at 18:09
(272) +74. This position lies in eastern Draco near the faint star Chi
Draconis. The radiant is best placed just as soon as it becomes dark, when
it lies highest in a dark sky. Meteors from the October Ursa Minorids strike
the atmosphere at 28km/sec., which would produce meteors of slow velocity.
Expected rates would be less than one per hour, as seen from the northern
hemisphere. Activity from this shower is not visible in the southern
hemisphere due to the high northerly location of the radiant.

The Northern Taurids (NTA) are active from a large radiant centered at 02:52
(043) +20, which lies in central Aries, five degrees west of the fourth
magnitude star Delta Arietis. The radiant is best placed near 0200 LDT, when
it lies highest above the horizon. Meteors from the Northern Taurids strike
the atmosphere at 29km/sec., which would produce meteors of slow velocity.
Expected rates would be near one per hour, no matter your location.

The center of the large Southern Taurid (STA) radiant lies at 02:58 (044)
+11. This position lies on the Aries/Cetus border, three degrees east of the
fourth magnitude star Mu Ceti. The radiant is best placed near the meridian
at 0200 LDT, 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 two per hour no matter your
location.

A new radiant has been discovered in Taurus which is active during this
period. The Eta Taurids (ETT) are active from October 25 through November 3,
with maximum occurring on the 25th. The current radiant position lies at
03:42 (056) +24, which lies in western Taurus in the area of sky occupied by
the famous Pleiades star cluster. The radiant is best placed near 0300 LDT,
when it lies highest above the horizon. Meteors from the Eta Taurids strike
the atmosphere at 47km/sec., which would produce meteors of average
velocity. Expected rates would be less than one per hour, no matter your
location.

The Orionids (ORI) reached maximum activity on the nights of October 21 and
22. Rates are now falling and will do so until the last Orionids are seen
near November 14. The radiant is currently located at 06:34 (98) +16. This
position lies in western Gemini very close to the second magnitude star
Alhena (Gamma Geminorum). The radiant is best placed near 0530 LDT, when it
lies highest above the horizon. Current rates would be near five per hour.
At 66km/sec., the average Orionid is swift.

The Epsilon Geminids (EGE) are active from October 16th through the 27th.
Maximum activity occurred on the 19th. The radiant is currently located at
07:09 (107) +27. This position lies in central Gemini, three degrees south
of the fourth magnitude star Tau Geminorum. This position is also close to
the Orionid radiant so care must taken for correct shower association,
especially since they have similar velocities. The Orionids will be more
numerous. Current rates are most likely less than one per hour. The radiant
is best placed near 0600 LDT, when it lies highest above the horizon. At
70km/sec., the average Epsilon Geminid is swift.

Recent studies by Sirko Molau has revealed a radiant in Cancer that is
active this time of year. The Beta Cancrids (BCN) are active from October 25
through November 3, with maximum occurring on the 27th. The current radiant
position lies at 07:16 (109) -09, which lies in southwestern Canis Minor,
seven degrees southwest of the brilliant zero magnitude star Procyon (Alpha
Canis Minoris. The radiant is best placed near 0600 LDT, when it lies
highest above the horizon.Meteors from the Beta Cancrids strike the
atmosphere at 65km/sec., which would produce meteors of swift velocity.
Expected rates would be less than one per hour, no matter your location.

The Leonis Minorids (LMI) are active from October 16-27 with maximum
activity occurring on October 23rd. ZHR's are usually low but the radiant is
far removed from the Orionids and Epsilon Geminids so that any possible
shower members should be easily identified. Hourly rates should be near one
this weekend. This radiant is currently located at 10:52 (163) +36, which
places it in northeastern Leo Minor, just northwest of the fourth magnitude
star 46 Leonis Minoris. The radiant is best placed just before dawn when it
lies highest in a dark sky. This shower is better situated for observers
situated in the northern hemisphere where the radiant rises far higher into
the sky before the start of morning twilight. At 60km/sec., the average
Leonis Minorid is swift.

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 three
per hour. As seen from the mid-southern hemisphere (45S), morning rates
would be near five per hour as seen from rural observing sites and one per
hour during the evening hours. Locations between these two extremes would
see activity between the listed figures. Moonlight reduces evening rates
this week.

The table below presents a condensed version of the expected activity this
week. Rates and positions are exact for Saturday night/Sunday morning.

October Ursa Minorids (OUI)  - 18:09 (272) +74 Velocity - 28km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr.

Northern Taurids (NTA)   - 02:52 (043) +20  Velocity - 29km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Southern Taurids (STA)  - 02:58 (044) +11  Velocity - 29km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr.

Eta Taurids (ETT) - 03:42 (056) +24   Velocity - 47km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Orionids (ORI)  - 06:34 (098) +16   Velocity - 67km/sec.
Northern Hemisphere - 5 per hr. Southern Hemisphere - 5 per hr.

Epsilon Geminids (EGE)  - 06:44 (101) +28   Velocity - 70km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Beta Cancrids (BCN)  - 07:16 (109) -09   Velocity - 65km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Leonis Minorids (LMI)  - 10:52 (163) +36   Velocity - 60km/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