(meteorobs) Meteor Activity Outlook for September 5-11, 2009

[Robert Lunsford]

September offers longer nights and cooler temperatures in the northern
hemisphere. In the sky, no major showers are visible from either hemisphere
but the northern hemisphere enjoys the advantage of higher sporadic rates.
The two recognized minor showers active in early September have high
northern declinations (celestial latitude) therefore are much better suited
to be viewed from locations north of the equator. During the second half of
the month the antihelion radiant becomes entangled with the two Taurid
radiants and it is impossible to separate them. Therefore the antihelion
radiant will be excluded from the list from the second half of September
until the end of the Taurid activity period late in November. Observers in
the southern hemisphere suffer from some of their lowest rates of the year
this month. The Taurid radiants are not too badly placed so observers south
of the equator can expect to see a little of this activity toward the end of
the month.

During this period the moon wanes from its full phase to nearly half
illuminated by the 11th. This weekend the nearly full moon will be in the
sky the entire night, making meteor observing difficult at best. As the week
progresses the moon will rise later in the evening with each passing night
but will still interfere with the prime morning observing hours. The
estimated total hourly rates for evening observers this week is near four as
seen from the northern hemisphere and one from the southern hemisphere. For
morning observers the estimated total hourly rates should be near six from
the northern hemisphere and two 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. Meteor rates are greatly reduced by moonlight all this
week.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning September 5/6. 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 full descriptions of each active meteor shower will continue next week
when the moon becomes less of a nuisance to observers.

The list below presents a condensed version of the expected activity this
week. Rates and positions are exact for Saturday night/Sunday morning.

Antihelion (ANT) - 23:44 (356.0) -01  Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr.

September Iota Cassiopeiids (SIC) - 02:24 (036.0) +60  Velocity - 50km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

September Epsilon Perseids (SPE) - 03:00 (045.0) +41  Velocity - 66km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Nu Eridanids (NUE) - 04:27 (066.7) -01  Velocity - 68km/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