(meteorobs) Meteor Activity Outlook for August 4-10, 2006

[Robert Lunsford]

During August observers in the northern hemisphere continue to see a rise in
the meteor activity, especially near August 12, when the Perseids reach
maximum strength. This peak is somewhat modified this year by the bright
gibbous moon that will be present during the Perseid maximum. Observers
south of the equator are seeing their rates plummet as the Perseids have
little effect in producing activity from the far southern latitudes.

This week the moon will reach its full phase on Wednesday August 9th. This
weekend the waxing gibbous moon will set during the early morning hours,
allowing a small window of opportunity between moonset and the start of
morning twilight, to observe in dark skies. As the week progresses, the moon
will be in the sky most of the night, interfering with observing. The
estimated total hourly rates for evening observers this week is near two no
matter your location. For morning observers the estimated total hourly rates
should be near twenty five for those in the northern hemisphere and eighteen
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. Evening rates are reduced due to moonlight.

The radiant positions listed below are exact for Saturday night/Sunday
morning August 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. 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 Kappa Cygnids (KCG) are active from a wide radiant located at 18:52
(283) +58. This position is located in southern Draco, four degrees
northwest of the fourth magnitude star Kappa Cygni. Current rates would be
near one shower member per hour. A large percentage of these meteors are
bright, often fireball class meteors with brilliant colors. With an entry
velocity of 25 km/sec. most of these meteors will appear to travel slower
than average. The radiant is best placed near 2300 Local Daylight Time (11pm
LDT) when it lies nearly overhead for much of the Northern Hemisphere. Due
to its high northern declination this activity is not well seen from the
Southern Hemisphere.

The Alpha Capricornids (CAP) are active from a wide radiant centered at
20:56 (314) -08. This area of the sky is centered in southwestern Aquarius,
just one degree northeast of the faint star Mu Aquarii. The radiant is best
placed near 0100 local daylight time, when it lies highest in the sky.
Current rates would be near one per hour, no matter your location. With an
entry velocity of 23 km/sec., most activity from this radiant would be slow.
This radiant is well seen except for far northern latitudes where it remains
twilight all night long and the radiant does not rise as high into their
sky. The Alpha Caps are also known for producing impressive fireballs.

The Antihelion (ANT) radiant is now centered at 21:44 (326) -12. This area
of the sky is centered in eastern Capricornus, three degrees north of the
third faint magnitude star Delta Capricornii. This radiant is best placed
near 0200 local daylight time when it lies on the meridian and is highest in
the sky. Rates at this time should be near one per hour for those north of
the equator and two per hour south of the equator. With an entry velocity of
30 km/sec., the average Antihelion meteor would be of medium-slow speed.
Please note that commencing in 2007; the International Meteor Organization
will suggest that visual observers include the North Delta Aquarids and both
branches of the Iota Aquarids as Antihelions. If observers wish to begin in
2006, the AMS has no objections.

The Southern Delta Aquarids (SDA) reached maximum activity on July 28, with
rates between 10 and 20, depending on your latitude. The radiant is
currently located at 23:04 (346) -14. This position lies in southern
Aquarius, three degrees northeast of the third magnitude star Delta Aquarii.
The radiant is best placed near 0300 local daylight time, when it lies
highest in the sky. Observers near 20 degrees south latitude are most
favored with longer nights and the radiant passing through the zenith. With
an entry velocity of 41 km/sec., most activity from this radiant would be of
average velocities. These meteors tend to be faint so the current rates with
all the moonlight present would only be near one shower member per hour, no
matter your location.

The Pisces Austrinids (PAU) also peaked on July 28 with a predicted ZHR of
five. Current rates, with all the moonlight present, would be less than one
per hour regardless of your location. The radiant is currently located at
23:16 (349) -27. This area of the sky lies four degrees northeast of the
bright star Fomalhaut (Alpha Piscis Austrini). These meteors are best seen
near 0300 LDT, when the radiant lies highest above the horizon. These
meteors are of average velocity, slower than the Aquarids but faster than
the Alpha Caps and the antihelion meteors.

Perseid (PER) activity is now near ten per hour, as seen from the northern
hemisphere. These rates will increase sharply as we approach the peak on the
morning of August 12. The current radiant position lies at 02:32 (038) +56,
which is located in extreme northwestern Perseus, three degrees west of the
fourth magnitude star Eta Persei. The radiant is well placed for those in
the Northern Hemisphere during the last few hours before dawn. Due to the
high northern declination (celestial latitude) of the radiant, rates seen
from the Southern Hemisphere are very low when compared to those seen north
of the equator. At 59 km/sec., Perseid meteors are swift, often exhibiting
persistent trains.

Sporadic rates continue to climb for observers located in the northern
hemisphere. One would expect to see perhaps twelve random meteors during the
last hour before dawn from rural observing sites. During the first dark hour
after the end of evening twilight, perhaps two random meteors can be seen
per hour. Sporadic rates increase as the night progresses so rates seen near
midnight would be near seven per hour. Sporadic rates seen from the southern
hemisphere are now falling rapidly. One would see approximately eleven
random meteors per hour during the last hour before dawn and two per hour
during the first dark hour after the end of evening twilight. Rates near
midnight would be near six per hour. Evening rates are reduced due to
moonlight.

Kappa Cygnids (KCG)   18:52 (283) +58
Northern Hemisphere  1 - Southern Hemisphere >1

Alpha Capricornids (CAP)  20:56 (314) -08
Northern Hemisphere  1 - Southern Hemisphere 1

Antihelion (ANT) - 21:44 (326) -12
Northern Hemisphere  1 - Southern Hemisphere 2

Southern Delta Aquarids (SDA)  23:04 (346) -14
Northern Hemisphere  1 - Southern Hemisphere 1

Pisces Austrinids (PAU)   23:16 (349) -27
Northern Hemisphere  >1 - Southern Hemisphere >1

Perseids (PER)   01:56 (029) +54
Northern Hemisphere  10 - Southern Hemisphere 3

*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