(meteorobs) Meteor Activity Outlook for June 3-9, 2005

Robert Lunsford lunro.imo.usa at cox.net
Thu Jun 2 13:17:36 EDT 2005


This upcoming period will see the moon reaching its new phase on Monday June
6. At this time the moon rises and sets with the sun and is not seen in the
night sky. Under these conditions this week will be the most favorable to
view the meteor activity in June. The estimated total hourly rates for
evening observers this week should be near two for those in the Northern
Hemisphere and three for those observers south of the equator. For morning
observers the estimated total hourly rates should be near six for those
located in the Northern Hemisphere and nine for those in the Southern
Hemisphere. 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 4/5. 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.

These are the showers that may be observed this week:

The Omega Scorpids (OSC) are listed among the radiants of the Dutch Meteor
Society. I once felt these meteors were part of the antihelion complex but
they now seem to be a separate source. The peak is listed as June 2 with a
ZHR of 5. Actual observed rates would be less unless one lives deep in the
Southern Hemisphere. The current radiant position is 15:40 (235) -20. This
area of the sky is located in eastern Libra, five degrees west of the third
magnitude double star Acrab (Beta Scorpii). The best time to view this
activity is near midnight, local daylight time, when the radiant lies on the
meridian and is positioned highest in the sky. With an entry velocity of 21
kilometers per second, these meteors will appear to move slowly.

The Anthelion radiant is now centered at 17:56 (269) -23. This area of the
sky is located in northwestern Sagittarius, five degrees northwest of the
third magnitude star Lambda Sagittarii. Since this radiant is large and
diffuse, any slow to medium speed meteor from northwestern Sagittarius,
southern Ophiuchus or southern Serpens Cauda could be a candidate for this
shower. The center of this area is best placed near 0200 local daylight time
when it lies on the meridian and is highest in the sky. At this time expect
to see two shower members per hour from the Southern Hemisphere and one from
the Northern.

Unlike most of the annual showers the antihelion source is produced by
debris from unknown objects orbiting in a direct motion like the earth.
These objects are most likely asteroids, which produce stony and metallic
debris whose density is much greater than material produced by comets. There
is also the possibility that some of this activity may be caused by the
"Jupiter family of comets", comets which have been altered by Jupiter's
gravity into much shorter orbits. This material collides with the earth on
the inbound portion of its orbit, before its closest approach to the sun.
Therefore we best see them just after midnight when we are facing the
direction from which this activity appears. The antihelion source is active
all year from an area of the sky nearly opposite that of the sun. The center
of this source will move approximately one degree eastward per day and
travels through many different constellations over the course of a year. It
may make sense to list these meteors as anthelions or "ANT" but a majority
of meteor organizations prefer that you list them from the constellation in
which the radiant is currently located or the constellation where the shower
reaches maximum activity. Observers who send their reports to the
International Meteor Organization (I.M.O.) should label these meteors as
Sagittarids (SAG).

The Arietids (DAR) are active from a radiant located approximately thirty
degrees west of the sun. The radiant rises just before the start of morning
twilight and any activity would be seen shooting upwards from the
northeastern horizon. These meteors are of medium velocity and usually last
several seconds as they skim the outer regions of the earth's atmosphere.
The current radiant position is located at 02:52 (043) +23 which is located
in central Aries some ten degrees east of the second magnitude star Hamal
(Alpha Arietis). This shower peaks on June 7 with a ZHR of 60. Even with
such strong rates the unfavorable altitude at the time of daybreak makes
seeing this activity a difficult challenge. On the other hand, those with
radio meteor equipment can easily detect this activity as it is the
strongest annual radio meteor shower of the year.

The Sporadic rates for the Northern Hemisphere are now reaching their low
plateau for the year. Observers can expect around five random meteors per
hour during the morning hours as seen from locations in the Northern
hemisphere. During the dark evening hours perhaps two random meteors can be
seen per hour north of the equator. Sporadic rates seen from the Southern
Hemisphere are slowly increasing toward a July maximum. From south of the
equator one would expect to see approximately seven random meteors per hour
during the late morning hours and three per hour during the evening.

Omega Scorpiids  (OSC)    16:08 (242) -20
Hourly Rate =     <1   N. Hemisphere,    1  S. Hemisphere

Anthelion  (Sagittarids)    17:56 (269) -23
Hourly Rate =     1   N. Hemisphere,    2  S. Hemisphere

Arietids (DAR)   02:52  (043)  +23
Hourly Rate =    1  N.  Hemisphere,   <1  S. Hemisphere

Clear Skies!
Robert Lunsford
American Meteor Society
http://www.amsmeteors.org/lunsford/




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