(meteorobs) Meteor Activity Outlook for June 23-29, 2006

[Robert Lunsford]

During June observers in the northern hemisphere see some of their lowest
rates of the year. During this month the sporadic rates bottom out producing
an average of only one meteor every ten minutes, even from dark sky sites.
The active showers are also modest this month, barely adding any more
activity to the nighttime scene. Observers south of the equator are enjoying
some of their best rates of the year. This activity is produced from strong
sporadic rates and the fact that the Antihelion radiant is positioned well
south of the celestial equator this time of year. Combine this activity with
long nights and the core of the Milky Way riding high in the sky, and you
get an impressive scene. Unfortunately we have so few southern observers to
enjoy this scenario. This is a reason that observations from south of the
equator are so important.

The short nights in the northern hemisphere often make June the least active
month for meteor observers. Many of the worlds most active meteor observers
suffer from twilight all night long this time of year so those who live in
the more temperate latitudes should make every effort to view the elusive
June activity and to report their valuable data.

This week the moon will reach its new phase on Sunday June 25th. On this
date the moon will rise and set with the sun and will not interfere with
meteor observing, no matter the hour. As the week progresses the waxing
crescent moon will enter the evening sky but will set well before the
morning active morning hours arrive. The estimated total hourly rates for
evening observers this week is near two for observers in the northern
hemisphere and four for those south of the equator. For morning observers
the estimated total hourly rates should be near eight for those in the
northern hemisphere and fifteen 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.

The radiant positions listed below are exact for Saturday night/Sunday
morning June 24/25. 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 are active this week from a radiant located at 14:52 (223)
+48. 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 are expected on June 27
but no outburst is expected this year so 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 19:04 (286) -22. This area
of the sky is located in central Sagittarius, very close to the position
occupied by the fourth magnitude star Omicron 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 are now
increasing toward a secondary maximum in July. One would see approximately
sixteen random meteors per hour during the last hour before dawn and four
per hour during the first dark hour after the end of evening twilight. Rates
near midnight would be near ten per hour.

June Bootids (JBO)   14:52 (223) +48
Northern Hemisphere - 1/hr - Southern Hemisphere ->1/hr.

Antihelion (ANT)   19:04 (286) -22

Northern Hemisphere - 2/hr - Southern Hemisphere -3/hr.

*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