Meteor Activity Outlook for June 28-July 4, 2008

After several months of low activity the meteor
rates for both hemispheres see a marked increase in July. In the northern hemisphere
the change is not noticable until mid-month when several southern radiants, the
Perseids, and sporadic rates all increase in activity. Southern rates are good all month long.

During this period the moon reaches its new
phase on Thursday July 3rd. At this time the moon will be located near the sun
and will not be visible at night. This weekend the waning crescent moon will
produce minor interference during the last few hours before dawn. As seen from the
mid-northern hemisphere (45 N) the estimated total hourly rates during the evening
observers would be near two. For morning observers the estimated total hourly rates
should be near ten. For those located in the mid-southern hemisphere (45 S) morning
rates would be near twenty and evening rates near four. 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 and rates listed below are exact
for Saturday night/Sunday morning June 28/29. 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. Viewing there 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 following showers are expected to be active this week:

A few June Bootids (JBO) may be seen during the evening hours radiating
from a position near 15:00 (225) +47. This area of the sky lies in northern Bootes,
six degrees north of the fourth magnitude star Beta Bootis. This radiant is best
placed as soon as it becomes dark. Rates at this time should be less than one
for those located in the northern hemisphere and near zero for observers south of
the equator. With an entry velocity of 18 km/sec., the average June Bootid meteor
would be of very slow speed.

The large Antihelion (ANT) radiant is now centered at 19:20 (290) -21.
This area of the sky lies in eastern Sagittarius, three degrees east of the
third magnitude star Pi Sagittarii. Actually any meteor from western Capricornus,
southern Aquila, as well as eastern Sagittarius could be a candidate for
this shower. This radiant is best placed near 0200 local daylight time (LDT) when it lies on the
meridian and is highest in the sky. Rates at this time should be near three for
northern observers and four for observers south of the equator. With an entry
velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

Studies by Sirko Molau of the IMO’s video data has revealed an active radiant
located in southeastern Aquila. Maximum activity was reached on June 25, but
activity continues through the 30th. The radiant lies at 20:16 (304) -07, which
is located ten degrees southeast of the bright first magnitude star Altair (Alpha
Aquilae). This radiant is best placed near 0300 LDT when it lies on the
meridian and is highest in the sky. Rates are most likely less than one per hour
regardless of your location. With an entry velocity of 40 km/sec., the average
North June Aquilid (NZC) meteor would be of medium speed, but noticably
more swift than the nearby Antihelion radiant.

As seen from the mid-northern hemisphere (45N) the Sporadic rates are
finally beginning to increase. One would expect to see approximately eight
random meteors during the last hour before dawn from rural observing sites and
two per hour during the evening hours. As seen from the mid-southern hemisphere
(45S) morning rates would be near seventeen per hour as seen from rural observing
sites and four per hour during the evening hours.

The table below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.