Meteor Activity Outlook for June 5-11, 2010

June is another slow month for meteor activity.
There are no major showers active in June and only the Antihelion source can be
counted on for continuous activity. Even the Antihelion is located so far south
this time of year that rates rarely exceed two per hour as seen from the northern
hemisphere. Sporadic rates reach their nadir in June as seen from the
mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern
hemisphere (45 S) continue to rise this month toward a maximum in July.

During this period the moon wanes from a fat
crescent down to a sliver that rises during the bright morning twilight. This
weekend the moon will rise during the morning hours but any interference it
causes can be easily avoided by keeping it out of your field of view. The lunar
glare will only be a small fraction of what it is at full moon so successful
meteor observing can be undertaken during this period. The
estimated total hourly rates for evening observers this week is near three for
northern observers and four for those viewing from south of the equator. For
morning observers the estimated total hourly rates should be near six from the
northern hemisphere and sixteen as seen from the southern hemisphere. 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.
Morning rates are slightly reduced during this period due to moonlight.

The radiant (the area of the sky where meteors appear
to shoot from) positions and rates listed below are exact for Saturday night/Sunday
morning June 5/6. 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:

The wide Antihelion (ANT) radiant is now centered at 17:52 (268) -23. This
area of the sky lies in western Sagittarius some ten degrees northwest of the second
magnitude star Lambda Sagittarii. This radiant is best placed near 0200 local
daylight time (LDT) when it lies on the meridian and is located highest in the sky.
Due to the large size of this radiant, any meteor radiating from southern Ophiuchus,
southern Serpens Cauda, western Sagittarius, or Scorpius could be a candidate for
this shower. Rates at this time should be near one per hour as seen from the northern
hemisphere and two per hour as seen from south of the equator. With an entry velocity
of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately
five sporadic meteors per hour during the last hour before dawn as seen from
rural observing sites. Evening rates would be near two per hour. As seen from the
mid-southern hemisphere (45S), morning rates would be near fourteen per hour as seen
from rural observing sites and three per hour during the evening hours. Locations
between these two extremes would see activity between the listed figures.
Morning rates are slightly reduced due to moonlight.

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