(meteorobs) Meteor Activity Outlook for June 30-July 6, 2006

[Robert Lunsford]

During July observers in the northern hemisphere witness a surge in meteor
activity, especially during the second half of the month. The source of this
increase is increased sporadic rates along with several showers located
opposite the sun. The Perseids also become active in mid-July with
increasing rates as the Earth nears the August 12 maximum. During the first
week of the month, observers south of the equator are enjoying some of their
best rates of the year. This activity is produced by the strongest sporadic
rates of the year and the fact that the Antihelion radiant is positioned
well south of the celestial equator this time of year. During the second
half of the month the sporadic rates begin to plummet and are the equal of
rates seen in the northern hemisphere by the end of the month.

This week the moon will reach its first quarter phase on Monday July 3rd.
This weekend the moon will set near midnight local daylight time and will
not interfere with meteor observing during the active morning hours. As the
week progresses the waxing gibbous moon will pose more of a problem as it
intrudes into the morning sky. The estimated total hourly rates for evening
observers this week is near two for observers in the northern hemisphere and
three for those south of the equator. For morning observers the estimated
total hourly rates should be near ten for those in the northern hemisphere
and twenty 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 July 1/2. 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 June Bootids (JBO) are active this week from a radiant located at 15:04
(226) +46. This area of the sky is located in northern Bootes some fifteen
degrees southeast of Alkaid (Eta Ursae Majoris), the last star in the handle
of the "Big Dipper". Due to the northern declination this shower is well
seen only from the southern equatorial areas northward to the northern
temperate areas. Those located north of 50 degrees north latitude will have
difficulty seeing any activity due to the very short nights experienced in
those latitudes this time of year. This area of the sky is best placed as
soon as it gets dark during the evening hours. Peak rates were expected on
June 27 so current rates will most likely be quite low. At 18 km/sec. any
June Bootids will appear to move quite slowly compared to most meteors.

The Antihelion (ANT) radiant is now centered at 19:32 (293) -20. This area
of the sky is located in eastern Sagittarius, five degrees northeast of the
third magnitude star Pi Sagittarii. 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 two per hour for those north of the
equator and three per hour south of the equator. With an entry velocity of
30 km/sec., the average Antihelion meteor would be of medium-slow speed.

After six months of declining rates the Sporadic rates for the Northern
Hemisphere are now finally starting to increase. One would expect to see
perhaps eight 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
five per hour. Sporadic rates seen from the southern hemisphere have now
reached a secondary maximum. One would see approximately seventeen random
meteors per hour during the last hour before dawn and three per hour during
the first dark hour after the end of evening twilight. Rates near midnight
would be near ten per hour. Evening rates are reduced due to moonlight.

June Bootids (JBO)  15:04 (226) +46
Northern Hemisphere 1 - Southern Hemisphere >1

Antihelion (ANT)   19:32 (293) -20 30 02:00 2 - 3 II
Northern Hemisphere 2 - 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