(meteorobs) Meteor Activity Outlook for September 22-28, 2006

[Robert Lunsford]

Although there are no major showers active in September, meteor rates in
the northern hemisphere continue to be strong. Minor activity from the
constellations of Auriga, Perseus, and Taurus, as well as strong sporadic
rates, produce these impressive rates. Rates as seen from the southern
hemisphere have dropped off significantly since the July peak. Other than
weak sporadic rates, only the antihelion radiant produces any notable shower
activity in the southern skies.

The moon reaches its new phase on Friday September 22. At this time it will
lie in the vicinity of the sun and will not interfere with meteor observing.
Next week the moon will enter the evening sky as a waxing crescent but will
set long before the prime meteor observing hours. The estimated total hourly
rates for evening observers this week is near three for those north of the
equator and one for those south of the equator. For morning observers the
estimated total hourly rates should be near eighteen for those in the
northern hemisphere and seven for those south of the equator. 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.

The radiant positions listed below are exact for Saturday night/Sunday
morning September 23/24. 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. 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.

These showers are expected to be active this week:

The large, diffuse Antihelion (ANT) radiant is now centered at 00:52 (013)
+07. This area of the sky is centered in southern Pisces, two degrees south
of the fourth magnitude star Delta Piscium. This radiant is above the
horizon most of the night but is best placed near 0200 local daylight time
(LDT), when it lies on the meridian and is located highest in the sky. Rates
at this time should be near two per hour regardless of your location. With
an entry velocity of 30 km/sec., the average antihelion meteor would be of
medium-slow speed. Starting with next week's report, the antihelion radiant
will be replaced by the two Taurid radiants. From then through the end of
November it will be impossible for the visual observer to accurately
separate this activity.

The Delta Aurigids (DAU) reach peak activity in early October. Current rates
have actually been a bit higher than normal with 1-2 shower members
appearing each hour. The radiant is located at 05:04 (76) +49. This position
lies in northwestern Auriga, three degrees northwest of the brilliant zero
magnitude star Capella (Alpha Aurigae). As seen from the northern
hemisphere, the radiant is above the horizon most of the night and is best
placed near 0500 LDT, when it lies on the meridian. Due to the extreme
northern declination of this radiant, this shower is only visible from the
southern tropics northward. At 64km/sec., the average Delta Aurigid is
swift.

A study of the IMO video database by Sirko Molau has shown that there is an
active radiant in the constellation of Orion this time of year. This is not
the well known Orionid shower, but rather a weak radiant located near
Bellatrix (Gamma Orionis). This activity has been recorded from September
24-30 with peak rates near the 27th. The position of this radiant on Sunday
morning is expected to be near 05:08 (77) +07 or three degrees west of the
second magnitude Bellatrix. This area of the sky is above the horizon most
of the night and is best placed near 0500 LDT, when it lies on the meridian.
With the radiant lying just north of the celestial equator, this shower
would be visible over most of the Earth. Meteors from this radiant strike
the Earth with a velocity of 59km/sec. This would produce mostly swift
meteors.

Sporadic rates continue to climb slowly for observers located in the
northern hemisphere. One would expect to see perhaps fourteen random meteors
during the last hour before dawn from rural observing sites. During the
first dark hour after the end of evening twilight, perhaps three random
meteors can be seen per hour. Sporadic rates increase as the night
progresses so rates seen near midnight would be near eight per hour.
Sporadic rates seen from the southern hemisphere have reached their annual
minimum. One would expect to see approximately four random meteors per hour
during the last hour before dawn and one per hour during the first dark hour
after the end of evening twilight. Rates near midnight would be near three
per hour.

Antihelion (ANT) - 00:28 (007) +03
Northern Hemisphere - 2   Southern Hemisphere - 2

Delta Aurigids (DAU)  05:04 (076) +49
Northern Hemisphere - 1   Southern Hemisphere - >1

                                   05:08 (077) +07
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#X2006

Clear Skies!
Robert Lunsford
American Meteor Society