(meteorobs) Meteor Activity Outlook for November 1-7, 2008

Robert Lunsford lunro.imo.usa at cox.net
Fri Oct 31 16:22:45 EDT 2008


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 first quarter phase on Thursday
November 6th. At this time the moon will be located ninety degrees east of
the sun and will set near midnight local standard time. This weekend the
waxing crescent moon will set during the early evening and not interfere
with observing. The estimated total hourly rates for evening observers this
week is near five for those located in the mid-northern hemisphere (45 N)
and two for those viewing from the mid-southern hemisphere (45 S). For
morning observers the estimated total hourly rates should be near twenty
four for those located in the mid-northern hemisphere (45 N) and twelve for
those viewing from the mid-southern hemisphere (45 S). Locations between
these two extremes would see activity between the listed figures. 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. Evening rates are reduced due to
moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning November 1/2. 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 activity in Pisces and
then into Andromeda between November 1st and the 19th, peaking on the 5th.
The position at maximum activity is 01:32 (023) +30. This position lies on
the Pisces-Triangulum border, four degrees west of the third magnitude star
Alpha Trianguli. Visual activity is expected to be low, but detectable. The
Andromedid radiant is best placed near 2200 (10pm) local standard time. At
20km/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.

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. Although
the radiants actually lie in Aries during October, they reach maximum
activity in November when they are situated in the constellation of Taurus.

The center of the large Northern Taurid (NTA) radiant is now centered at
03:16 (049) +20. This position lies in eastern Aries near the fourth
magnitude star Delta Arietis. The center of the large Southern Taurid (STA)
radiant lies at 03:16 (049) +14. This position also lies in eastern Aries,
six degrees south of Delta Arietis. The two radiants are separated by
slightly over five 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 less difficult to distinguish
those meteors traveling east or west. These radiants are best placed near
the meridian at 0200 local daylight time (LDT). At 29 and 27 km/sec., the
average Taurid meteor travels slowly through the skies.

Sirko Molau's new studies of video radiants has revealed that the Northern
Taurid's reach two plateaus of activity with the first occurring on October
20th. The moon subdued this activity so it was most likely not noticed. The
secondary peak is predicted to occur near November 13th and will be severely
hampered by a bright moon. The same study has revealed that the Southern
Taurids may have peaked near October 11 and that the activity for this
shower will remain fairly constant through the first week of November. After
that rates will dwindle until these meteors disappear near the end of
November.

The Orionids (ORI) peaked on the morning of October 21st. Rates will now
dwindle until the shower is no longer detectable. The radiant is now located
at 06:48 (102) +16. This position lies in southwestern Gemini, two degrees
east of the second magnitude star Alhena (Gamma Geminorum). The radiant
rises near 2300 LDT and is best placed on the meridian near 0500. At
66km/sec., the average Orionid is swift.

Sirko Molau's studies of video radiants has revealed activity in northern
Cancer between October 10 and November 4, peaking on the October 14th. The
radiant for the Iota Cancrids (ICA) lies at 09:36 (144) +29. This position
lies in northwestern Leo, five degrees northwest of the fourth magnitude
star Upsilon Leonis. Visual activity is expected to be low, especially since
we are now two weeks past the peak. The radiant rises near 0200 LDT and is
best placed high in the east during the last dark hour of the morning. At
67km/sec., the average Iota Cancrid will appear move swiftly through the
skies.

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. Evening rates are reduced due to
moonlight.

The table below presents a summary of the expected activity this week. Rates
and positions are exact for Saturday night/Sunday morning but may be used
all week.

Andromedids (AND)  01:32 (023) +30   Velocity - 20km/sec.
Hourly Rates: Northern Hemisphere -  <1    Southern Hemisphere - <1

Northern Taurids (NTA)  03:16 (049) +20   Velocity - 29km/sec.
Hourly Rates: Northern Hemisphere -  3    Southern Hemisphere - 3

Southern Taurids (STA)  03:16 (049) +14   Velocity - 27km/sec.
Hourly Rates: Northern Hemisphere -  2    Southern Hemisphere - 2

Orionids (ORI)  06:48 (102) +16   Velocity - 66km/sec
Hourly Rates: Northern Hemisphere -  2    Southern Hemisphere - 2

Iota Cancrids (ICA)  09:36 (144) +29   Velocity - 67km/sec.
Hourly Rates: Northern Hemisphere -  <1    Southern Hemisphere - <1

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2008

Clear Skies!
Robert Lunsford
American Meteor Society




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