(meteorobs) Meteor Activity Outlook for June 15-21, 2007

[Robert Lunsford]

June is a slow month for meteor activity, especially as seen from the
northern hemisphere. The June Lyrids peak mid-month but add little to the
overall activity. The June Bootids peak near month's end but can be totally
absent. Sporadic rates as seen from the northern hemisphere are lowest this
month. From the southern hemisphere sporadic rates are quite strong with
much of this activity provided by unknown ecliptical radiants which ride
high in the sky this time of year as seen from south of the equator.

During this period the moon reaches its new phase on Friday June 15.
At this time the moon is located near the sun in the sky and is
not visible at night. Later during this period the waxing crescent moon 
enters the
evening sky but sets well before the more productive morning hours. The 
estimated
total hourly rates for evening observers this week is near two for those 
located
north of the equator and four for observers south of the equator. For
morning observers the estimated total hourly rates should be near nine for 
those
located in the northern hemisphere and eighteen for those viewing from 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 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. Doing this 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 Antihelion (ANT) radiant is now centered at 18:32 (278) -23. This area
of the sky is located in central Sagittarius, two degrees north of the third
magnitude star Lambda Sagittarii. This radiant is best placed near 0200 LDT,
when it lies on the meridian and is highest in the sky. Rates at this time
should be near two per hour as seen in the northern hemisphere and three per
hour for those located south of the equator. With an entry velocity of 30
km/sec., the average antihelion meteor would be of medium-slow speed.

The June Lyrids (JLY) are active from June 10 through the 21st with maximum
activity near the 16th. The radiant has a published position of 18:32 (278)
+35 but most of the recent activity has occurred from an area further north
toward Draco (Xi Draconids). Analysis of recent video results indicate a
sharp radiant near 18:32 (278) +45 so we suggest you use this position on
June 16 for classifying these meteors. This position lies in northern Lyra,
six degrees north of the zero magnitude star Vega (Alpha Lyrae). This
radiant culminates near 0200 local daylight saving time. Due to the high
northern position these meteors are best seen from the northern hemisphere.
With an entry velocity near 40 km/sec., the average June Lyrid meteor would
be of medium-fast speed.

Sporadic rates have bottomed out for observers in the northern hemisphere
and slightly rising for those located south of the equator. One would expect
to see perhaps seven random meteors during the last hour before dawn from
rural observing sites located in the northern hemisphere. 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 four per hour. Late morning sporadic rates
seen from the southern hemisphere are now near sixteen per hour from rural
observing sites. During the first dark hour after the end of evening
twilight, perhaps four random meteors can be seen per hour, increasing to
eight by midnight.

Antihelion (ANT) - 18:32 (278) -23
Northern Hemisphere - 1   Southern Hemisphere - 2

June Lyrids (JLY)  18:40 (280) +45
Northern Hemisphere - 1   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#X2007

Clear Skies!
Robert Lunsford
American Meteor Society