(meteorobs) Meteor Activity Outlook for October 16-22, 2010

[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 usually the big story of the month but this year the Orionid
peak coincides with the full moon, which will severely reduce the number of
meteors seen. Orionid activity can be seen before and after maximum when the
moon is not so troublesome. Unfortunately on these nights the Orionid rates
will be low, most likely less than five per hour.

During this period the moon waxes from just past its first quarter phase to
nearly full at the end of the period. This weekend the waxing gibbous moon
will set during the early morning hours and will allow a couple of hours of
dark skies before the beginning of twilight. This window of opportunity will
shrink as the week progresses becoming essentially zero by the end of the
week. The estimated total hourly rates for evening observers this week is
near three from the northern hemisphere and two for observers south of the
equator. For morning observers the estimated total hourly rates should be
near twenty four from the northern hemisphere and twelve 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 this
week due to lunar interference.

The radiant (the area of the sky where meteors appear to shoot from)
positions and rates listed below are exact for Saturday night/Sunday morning
October 16/17. 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:

Studies of the IMO video database by Sirko Molau and Juergen Rendtel has
revealed a radiant located in Draco this time of year. Earlier visual
observations placed the radiant in Ursa Minor therefore this shower is known
as the October Ursa Minorids (OUI). This shower is active from October 16-28
with maximum occurring on the 24th. The moon will greatly hamper
observations of this shower, especially near maximum on the 24th. On
Saturday evening the radiant is located at 18:44 (281) +76. This position
lies in western Draco some fifteen degrees south (above) Polaris (Alpha
Ursae Minoris). Although the radiant is circumpolar (never sets) for most of
the northern hemisphere, it is best placed as soon as it becomes dark.
Striking the atmosphere at 28 km/sec., the average October Ursa Minorid
meteor travels medium-slow through the sky. This shower is best seen from
high northern latitudes. It is almost impossible to see from the southern
hemisphere. Even at maximum, rates should be less than one per hour no
matter your location.

Recent studies of the IMO video database has revealed that activity from the
Northern Taurids (NTA) does not begin until October 19th. This is nearly one
month after pervious published dates. Maximum activity does not occur until
November 13th so current rates will be low, lower than its southern
counterpart until late in the month. The current radiant position lies near
02:28 (037) +18, which is located in central Aries, six degrees southeast of
the second magnitude star Hamal (Alpha Arietis). The radiant is best placed
near 0200 local daylight time (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 02:32 (038)
+10. This position lies on the Aries/Cetus border, three degrees west of the
fourth magnitude star Mu Ceti. Since the radiant is so large, any meteor
from eastern Pisces, northeastern Cetus, Aries, western Taurus, or
northeastern Eridanus could be a candidate for this shower. The radiant is
best placed near the meridian near 0200 LDT, but activity may be seen all
night long. Although maximum activity occurred on the 10th, this is a flat
plateau-like peak so activity should still be good this week. Expect to see
up to three Southern Taurids per hour, no matter your location, when the
radiant lies highest in the sky. Striking the atmosphere at 29 km/sec., the
average Southern Taurid meteor travels slowly through the skies. This shower
is also responsible for many of the fireball reports seen in October.

Another shower derived from the IMO video database is the Sigma Arietids
(SSA). This shower is active from October 12-19 with a peak on the 19th. The
radiant is located at 03:16 (049) +22. This position lies in eastern Aries,
four degrees northeast of the fourth magnitude star Delta Arietis. The
radiant is best placed near 0300 LDT, when it lies highest above the
horizon. Rates should less than one per hour. With an entry velocity of 46
km/sec., most activity from this radiant would be of medium velocity. These
meteors are well seen from all but the polar regions of the Earth.

Another shower derived from the IMO video database is the Zeta Taurids
(ZTA). This shower is active from October 12-17 with a peak on the 16th. The
radiant is located at 05:26 (081) +11. This position actually lies in Orion,
three degrees northwest of the third magnitude star Lambda Orionis. The
radiant is best placed near 0500 LDT, when it lies highest above the
horizon. Rates should less than one per hour. With an entry velocity of 61
km/sec., most activity from this radiant would be swift. These meteors would
be seen equally well from either hemisphere.

The Orionids (ORI) reach maximum activity on Friday October 22nd.
Unfortunately a nearby full moon will spoil the display. The radiant is
currently located at 06:08 (092) +16. This position lies in northeastern
Orion, very close to the fourth magnitude star Nu Orionis. The radiant rises
near 300 LDT and is best placed on the meridian near 0500. Current rates for
all locations would be near three to five per hour as seen after midnight.
At 67km/sec., the average Orionid is swift.

The Epsilon Geminids (EGE) are active from October 16th through the 27th.
Maximum activity occurs on the 19th. The radiant is currently located at
06:40 (100) +29. This position lies on the Gemini/Auriga border, four
degrees northwest of the third magnitude star Mebsuta (Epsilon Geminorum).
This position is also close to the Orionid radiant. Care must taken for
correct shower association. The Orionids will be far more numerous. Current
rates are probably near one per hour for the northern hemisphere and less
than one as seen from south of the equator. The radiant is best placed near
0600 LDT, when it lies highest above the horizon. At 70km/sec., the average
Epsilon Geminid is swift.

Another shower derived from the IMO video database is the October Ursa
Majorids (OCU). This shower is active from October 12-19 with a peak on the
15th. On the 12th the radiant is located at 09:52 (148) +63. This position
lies in western Ursa Major, fifteen degrees west of the second magnitude
star Dubhe (Alpha Ursae Majoris). The radiant is best placed during the last
dark hour before dawn when it lies highest above the horizon in a dark sky.
Rates should less than one per hour. With an entry velocity of 53 km/sec.,
most activity from this radiant would be medium-swift. With the high
northern declination of the radiant, these meteors are best seen from the
northern hemisphere. It would be difficult to see any of this activity from
locations south of the equator.

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 would be less than
one this week. This radiant is currently located at 10:16 (154) +35, which
places it in northeastern Leo Minor, two degrees southwest of the fourth
magnitude star Beta 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 fifteen sporadic meteors per hour during the last hour before
dawn as seen from rural observing sites. Evening rates would be near two per
hour. As seen from the mid-southern hemisphere (45S), morning rates would be
near four 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. Evening rates are reduced due to
moonlight.

The list 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) - 18:44 (281) +76   Velocity - 28km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Northern Taurids (NTA) - 02:28 (037) +18   Velocity - 29km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr.

Southern Taurids (STA) - 02:32 (038) +10   Velocity - 29km/sec.
Northern Hemisphere - 3 per hr. Southern Hemisphere - 3 per hr.

Sigma Arietids (SSA) - 03:16 (049) +22   Velocity - 46km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Zeta Taurids (ZTA) - 05:26 (081) +11   Velocity - 61km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Orionids (ORI)  - 06:08 (092) +16   Velocity - 67km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr

Epsilon Geminids (EGE)  - 06:40 (100) +29   Velocity - 70km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - <1 per hr

October Ursa Majorids (OCU)  - 09:12 (138) +64   Velocity - 53km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Leonis Minorids (LMI)  - 10:16 (154) +35   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#X2010

Clear Skies!
Robert Lunsford
American Meteor Society