(meteorobs) Meteor Activity Outlook for October 4-10, 2008

[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
21st. 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 Tuesday
October 7th. At this time the moon will be located ninety degrees east of
the sun and will set near 0100 local daylight time (LDT). This will allow
excellent conditions during the more active morning hours. 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 for those located in the
mid-northern hemisphere (45 N) and ten 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 slightly reduced due to moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning October 4/5. 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:

The Draconids (GIA) (also known as the Giacobinids) reach maximum activity
on October 8. The exact time of maximum activity can vary so observers are
encouraged to view on the evenings of October 7-9 to try and catch any of
this activity.The radiant is located at 17:28 (262) +54, which places it in
southern Draco, two degrees northwest of the third magnitude star Rastaban
(Beta Draconis). This star is one of the four that form the prominent head
of Draco, also known as the "Lozenge". Expected rates are always a guess.
The first quarter moon will slightly interfere. Those located in high
northern latitudes can also try viewing this shower during the morning hours
when the moon is absent. Due to the extreme northern declination, this
shower is only visible from the southern tropics northward. The radiant is
best placed just as it becomes dark during the evening hours. At 20km/sec.,
the average Draconid is extremely slow.

The center of the large Northern Taurid (NTA) radiant is now centered at
01:44 (026) +14. This position lies in eastern Pisces, two degrees southeast
of the fourth magnitude star Eta Piscium. The center of the large Southern
Taurid (STA) radiant lies at 01:52 (028) +08. This position also lies in
eastern Pisces, near the fourth magnitude star Omicron Piscium. The two
radiants are separated by slightly over five degrees. Since they have nearly
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 LDT. At 29 and 27
km/sec., the average Taurid meteor travels slowly through the skies.

The Orionids (ORI) are now becoming noticeable from a radiant located at
05:40 (85) +14. This position lies in northern Orion, six degrees northwest
of the orange first magnitude star Betelgeuse (Alpha Orionis). The radiant
rises near 2300 LDT and is best placed on the meridian near 0500. With
maximum activity predicted for October 21, current rates for all locations
would be near one to two per hour as seen after midnight. At 66km/sec., the
average Orionid is swift.

The Delta Aurigids (DAU) are present in the morning skies in the second half
of September and early October. Maximum activity occurred on October 3rd 
with
an average ZHR of two. Current rates will be most likely near one per hour
as seen from the northern hemisphere and less than one as seen from the
south of the equator. The radiant is currently located 05:56 (089) +49. This
position lies in northwestern Auriga, five degrees northeast of the zero
magnitude star Capella (Alpha Aurigae). At 64km/sec., the average Delta
Aurigid is swift.

During 2005 and 2006 a shower of bright meteors has occurred on October 5th
and 6th, radiating from near the Draco/Camelopardalis border. The 2007
display was missed due to moonlight and clouds. The October Camelopardalids
(OCT) peak for only a few hours but shower members are bright and should be
easy to observe. The 2008 display is predicted to occur near 14 UT on
October 5th, which corresponds to 0700 PST. It is daylight at this time from
the USA's west coast but observers along the Pacific coast of Canada and
Alaska can view at this time. The last hour before dawn may provide some
activity as seen from the western USA and Canada. The estimated position of
the radiant on the 5th is 10:48 (162) +79. The nearest easy star to identify
the radiant is 4th magnitude SAO1551. Polaris (Alpha Ursae Minoris) lies 12
degrees to the north. This area of the sky is circumpolar from nearly the
entire northern hemisphere. The radiant lies highest above the horizon in a
dark sky at both dusk and at dawn. Due to this unusual situation this shower
would be totally invisible from the southern hemisphere. With an entry
velocity of 47 miles per second most members of the October Camelopardalids
would be of medium-swift velocity. Shower members should be seen from
October 1-10, but at very low numbers away from the peak hour on the 5th.

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 three
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. Rates are slightly reduced during
the evening hours 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.

Draconids (GIA)   17:28 (262) +54  Velocity -  20km/sec.
Hourly Rates: Northern Hemisphere -  <1    Southern Hemisphere - <1

Northern Taurid (NTA)   01:44 (026) +14   Velocity - 29km/sec.
Hourly Rates:  Northern Hemisphere -  2    Southern Hemisphere - 2

Southern Taurid (STA)   01:52 (028) +08  Velocity - 27km/sec.
Hourly Rates:  Northern Hemisphere -  3    Southern Hemisphere - 3

Orionids (ORI)   05:40 (85) +14   Velocity - 66km/sec.
Hourly Rates:  Northern Hemisphere -  1    Southern Hemisphere - 1

Delta Aurigids (DAU)   03 05:56 (089) +49  Velocity -  64km/sec.
Hourly Rates:  Northern Hemisphere -  <1    Southern Hemisphere - <1

October Camelopardalids (OCT)   10:48 (162) +79 Velocity - 47km/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