(meteorobs) Meteor Activity Outlook for October 10-16, 2009

Robert Lunsford lunro.imo.usa at cox.net
Thu Oct 8 18:20:15 EDT 2009


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 last quarter phase on Sunday October
11th. At this time the moon rises near 0100 local daylight time (LDT) and
remains in the sky the remainder of the night. The situation improves as the
week progresses with the moon waning into a crescent phase and rising later
in the night with each passing morning. The estimated total hourly rates for
evening observers this week is near four as seen from the northern
hemisphere and two from the southern hemisphere. For morning observers the
estimated total hourly rates should be near fifteen 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. Morning rates are reduced by moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning October 10/11. 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 recent study of video radiants by Sirko Molau has revealed a radiant in
Pisces active from October 7-11. Maximum activity occurs on the 9th from a
radiant located at 0:05 (001) +14. This position is located on the
Pisces/Pegasus border, three degrees southwest of the 3rd magnitude star
Algenib (Gamma Pegasi). The radiant is best placed near 0100 LDT, when it
lies highest above the horizon. Meteors from the October Epsilon Piscids
(OPC) strike the atmosphere at only 19km/sec., which would produce slow
moving meteors. Expected rates would be less than one per hour, no matter
your location.

The center of the large Southern Taurid (STA) radiant lies at 02:10 (032)
+09. This position lies on the Pisces/Cetus border, one degree west of the
fourth magnitude star Xi Ceti. Since the radiant is so large, any meteor
from eastern Pisces, northern Cetus, or southwestern Aries could be a
candidate for this shower. 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 three per hour no matter your location.

A new radiant has been discovered in Aries which is active during this
period. The Sigma Arietids (SSA) are active from October 12-19, with maximum
occurring on the 19th. The current radiant position lies at 02:52 (043) +22,
which lies in eastern Aries, six degrees south of the faint star 41 Arietis.
The radiant is best placed near 0300 LDT, when it lies highest above the
horizon. Meteors from the Sigma Arietids strike the atmosphere at 45km/sec.,
which would produce meteors of average velocity. Expected rates would be
less than one per hour, no matter your location.

Another new radiant has been discovered in Taurus which is active during
this period. The Zeta Taurids (ZTA) are active from October 12-17, with
maximum occurring on the 16th. The current radiant position lies at 05:06
(076) +15, which lies on the Taurus/Orion border, six degrees east of the
bright first magnitude orange star Aldebaran (Alpha Tauri). The radiant is
best placed near 0500 LDT, when it lies highest above the horizon. Meteors
from the Zeta Taurids strike the atmosphere at 61km/sec., which would
produce meteors of swift velocity. Expected rates would be less than one per
hour, no matter your location.

The Orionids (ORI) are now becoming more active from a radiant located at
05:50 (87) +15. This position lies on the Orion/Taurus border, seven degrees
north of the orange first magnitude star Betelgeuse (Alpha Orionis). The
radiant rises near 2300 LDT and is best placed on the meridian near 0600.
With maximum activity predicted for October 22, current rates for all
locations would be near two to three per hour as seen after midnight. At
66km/sec., the average Orionid is swift.

Activity from Ursa Major this time of year has been known for several years
now. Recent studies by Sirko Molau has provided more precise data on this
activity. The October Ursa Majorids (OCU) are active from October 12-19,
with maximum occurring on the 15th. The current radiant position lies at
09:12 (138) +63, which lies in western Ursa Major, two degrees west of the
faint star 23 Ursae Majoris. The radiant is best placed during the last dark
hour before the start of morning twilight, when it highest above the horizon
in a dark sky. Meteors from the October Ursa Majorids strike the atmosphere
at 53km/sec., which would produce meteors of medium-swift velocity. Expected
rates would be less than one per hour, no matter your location. This
activity is not visible from the southern hemisphere due to the high
northerly declination of the radiant.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately eight 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 two 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. Rates are reduced during the
morning hours 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 except
for showers of short duration, when the position on the night of maximum is
listed.

October Epsilon Piscids (OPC)  - 00:05 (001) +14   Velocity - 19km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Southern Taurids (STA)  - 02:10 (032) +09  Velocity - 29km/sec.
Northern Hemisphere - 3 per hr. Southern Hemisphere - 3 per hr.

Sigma Arietids (SSA) - 02:52 (043) +22   Velocity - 45km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Zeta Taurids (ZTA)  - 05:06 (076) +15   Velocity - 61km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Orionids (ORI)  - 05:50 (087) +15   Velocity - 67km/sec.
Northern Hemisphere - 3 per hr. Southern Hemisphere - 3 per hr.

October Ursa Majorids (OCU)  - 09:12 (138) +63   Velocity - 53km/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




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