(meteorobs) Meteor Activity Outlook for September 13-19, 2008

Robert Lunsford lunro.imo.usa at cox.net
Fri Sep 12 01:11:53 EDT 2008


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. Toward the end 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 last week 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 reaches its full phase on Monday September 15.
At this time the moon will rise near evening twilight and will remain in the
sky all night long. As the week progresses the moon will rise later in the
evening giving a growing window of darkness just after evening twilight. The
more active morning hours will still suffer from the intense moonlight. The
estimated total hourly rates for evening observers this week is near two for
those located in the mid-northern hemisphere (45 N) and one for those
viewing from the mid-southern hemisphere (45 S). For morning observers the
estimated total hourly rates should be near eight for those located in the
mid-northern hemisphere (45 N) and five for those viewing from the
mid-southern hemisphere (45 S). 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. Rates are reduced this week due to intense moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning September 13/14. 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.

Antihelion (ANT)   00:16 (004) +03   Velocity - 30km/sec.
Northern Hemisphere - 1   Southern Hemisphere - 1

September Perseids (SPE)   04:20 (065) +48   Velocity - 64km/sec.
Northern Hemisphere - <1   Southern Hemisphere - <1

Northern September Lyncids (NSL)   07:36 (114) +56   Velocity 53km/sec.
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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