(meteorobs) Meteor Activity Outlook for August 5-11, 2005

Robert Lunsford lunro.imo.usa at cox.net
Fri Aug 5 01:00:35 EDT 2005


This upcoming period will see the moon reaching its new phase on Friday
August 5. By Sunday, the very slender waxing moon will enter the evening
sky.  It's percentage of illumination will increase with each passing
evening. By Thursday August 11, the fat crescent moon, some forty percent
illuminated, will set near midnight local daylight time. The estimated total
hourly rates for evening observers this week should be near three for
Northern Hemisphere observers and two for those located in the Southern
Hemisphere.. For morning observers the estimated total hourly rates should
be near twenty-five for Northern Hemisphere observers and fifteen for those
located in the Southern Hemisphere. 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 August 6/7. 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 are the showers that may be observed this week:

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 located at 21:00
(315) -08. This position lies in western Aquarius, three degrees northeast
of the fourth magnitude star Epsilon 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 Anthelion radiant is now centered at 21:56 (329) -11. This area of the
sky is located in northeastern Capricornus, six degrees northeast of the
third magnitude star Nashira (Delta Capricornii). Since this radiant is
large and diffuse, any slow to medium speed meteor from eastern Capricornus
or western Aquarius could be a candidate for this shower. The center of this
area is best placed near 0200 local daylight time when it lies on the
meridian and is highest in the sky. At this time expect to see two shower
members per no matter your location.

Unlike most of the annual showers the antihelion source is produced by
debris from unknown objects orbiting in a direct motion like the earth.
These objects are most likely asteroids, which produce stony and metallic
debris whose density is much greater than material produced by comets. There
is also the possibility that some of this activity may be caused by the
"Jupiter family of comets", comets which have been altered by Jupiter's
gravity into much shorter orbits. This material collides with the earth on
the inbound portion of its orbit, before its closest approach to the sun.
Therefore we best see them just after midnight when we are facing the
direction from which this activity appears. The antihelion source is active
all year from an area of the sky nearly opposite that of the sun. The center
of this source will move approximately one degree eastward per day and
travels through many different constellations over the course of a year. It
may make sense to list these meteors as anthelions or "ANT" but a majority
of meteor organizations prefer that you list them from the constellation in
which the radiant is currently located or the constellation where the shower
reaches maximum activity.

The North Delta Aquarids (NDA) are currently active from a radiant located
at 22:12 (333) -06. This area of the sky is located in central Aquarius,
five degrees southeast of the third magnitude star Sadalmelik (Alpha
Aquarii). At 42 km/sec. the NDA's are a bit faster than your average meteor.
This radiant is most active near 0200 LDT when it lies highest in the sky.
Current hourly rates should be near one shower member per hour, no matter
your location. This shower is predicted to peak near August 8 with ZHR's of
four. Be careful when distinguishing this shower as the Anthelion radiant
lies quite close.

The Southern Iota Aquarids (SIA) peak on August 4 with a ZHR of two. With
these low rates one would be lucky to see one shower member per hour. The
radiant is currently located at 22:24 (336) -15. This area of the sky is
located in southwestern Aquarius, five degrees west of the third magnitude
star Delta Aquarii. At 34 km/sec. the SIA's would possess medium to slow
velocities. This radiant is most active near 0200 LDT when it lies highest
in the sky.

The Southern Delta Aquarids (SDA) are active from a radiant located at 23:08
(347) -14. This position lies in western Aquarius, four degrees northeast of
the third magnitude star Delta Aquarii. The radiant is best placed near 0400
local daylight time, when it lies highest in the sky. Currently rates would
be 2-3 per hour, depending on how high the radiant is located in your sky.
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 darkest
skies are necessary in order to see this shower well. This shower peaked on
July 28.

The Pisces Austrinids (PAU) are currently active from a radiant located at
23:20 (350) -27. This area of the sky lies in eastern Pisces Austrinus, five
degrees northeast of the first magnitude star Fomalhaut (Alpha Piscis
Austrini). This shower peaked on the July 28 with ZHR's of three. Current
rates would be near one per hour as seen from the most favored southern
latitudes, where the radiant rises higher in the sky. From the Northern
Hemisphere rates would only be less one per hour since the radiant does not
climb high into the sky. 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 strengthening with each passing night. The current
radiant position lies at 02:36 (039) +57, which is located in northwestern
Perseus, two degrees west of the famous "Double Cluster" (h and x Persei) on
most star charts. 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 or non-existent. Current Perseid rates for
those located north of the equator should be near seven per hour. These
rates will gradually increase as we approach the August 12 maximum. By the
end of this period, Perseid rates should be nearing thirty an hour during
the last portion of the night. At 59 km/sec., Perseid meteors are swift,
often exhibiting persistent trains. For more information on the 2005 Perseid
display. Please visit the AMS website at:
http://www.amsmeteors.org/visual.html#Perseids

The Sporadic rates for the Northern Hemisphere are now quickly rising from
their low plateau for the year. Observers can expect around eight random
meteors per hour during the morning hours as seen from locations in the
Northern hemisphere. During the dark evening hours perhaps three random
meteors can be seen per hour north of the equator. Sporadic rates seen from
the Southern Hemisphere are falling from a secondary annual maximum in July.
>From south of the equator one would expect to see approximately six random
meteors per hour during the late morning hours and two per hour during the
evening.

Kappa Cygnids (KCG)   18:52 (283) +58
Hourly Rate = N. Hemisphere 1 - S. Hemisphere <1

Alpha Capricornids (CAP)   21:00 (315) -08
Hourly Rate = N. Hemisphere 1 - S. Hemisphere 1

Anthelion    21:56 (329) -11
Hourly Rate = N. Hemisphere 2 - S. Hemisphere 2

Northern Delta Aquarids (NDA)   22:12 (333) -06
Hourly Rate = N. Hemisphere 1 - S. Hemisphere 1

Southern Iota Aquarids (SIA)   22:24 (336) -15
Hourly Rate = N. Hemisphere 1 - S. Hemisphere 1

Southern Delta Aquarids (SDA)   23:08 (347) -14
Hourly Rate = N. Hemisphere 2 - S. Hemisphere 3

Piscis Austrinids (PAU)   23:20 (350) -27
Hourly Rate = N. Hemisphere <1 - S. Hemisphere 1

Perseids (PER)   02:36 (039) +57
Hourly Rate = N. Hemisphere 7 - S. Hemisphere <1

Clear Skies!
Robert Lunsford
American Meteor Society



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