(meteorobs) Meteor Activity Outlook for August 16-22, 2008

[Robert Lunsford]

Meteor activity kicks into high gear in August as seen from the northern
hemisphere. The main reason for all this activity is the Perseid shower that
peaks on August 12. The shower is active most of the month and remains above
the level of the sporadic background for a week centered on August 12. The
sporadic activity is also increasing as seen from the northern hemisphere
and is now nearly double the rates from just three months ago. As seen from
south of the equator, meteor rates are still decent but falling rapidly. The
sporadic rates seen at the beginning of the month will be twice as much as
those seen during the last days of the month. The Perseid radiant does not
rise high into the sky as seen in the southern hemisphere so rates from this
shower are greatly reduced when compared to the northern hemisphere.

During this period the moon reaches its full phase on Saturday August 16. 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. Good
opportunities to view the weak evening showers such as the Kappa Cygnids and
the August Capricornids are possible later in the week. The estimated total
hourly rates for evening observers this week is near three 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 twelve 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 August 16/17. 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 table below presents a condensed version of the expected activity this
week. Rates and positions are exact for Saturday night/Sunday morning.

Kappa Cygnids (KCG)   19:00 (285) +59   Velocity - 25km/sec.
Northern Hemisphere - 1   Southern Hemisphere - <1

August Capricornids (AUC)   20:04 (301) -09   Velocity - 19km/sec.
Northern Hemisphere - <1   Southern Hemisphere - <1

Antihelion (ANT)   22:28 (337) -08   Velocity - 30km/sec.
Northern Hemisphere - 1   Southern Hemisphere - 1

Delta Aquariids (SDA)   23:36 (354) -12   Velocity - 41km.sec.
Northern Hemisphere - <1   Southern Hemisphere - <1

Perseids (PER)   03:36 (054) +58   Velocity - 57km/sec.
Northern Hemisphere - 5   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