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(meteorobs) Meteor Activity Outlook March 31- April 6, 2000



This will be the best week in April to watch for meteor activity. The
moon will be new  on the Tuesday the 4th meaning that the entire night
will be free of any lunar interference. If you are only free to view on
weekends then the  moon will be a waning crescent low in the
southeastern sky at dawn. It will be thin and will not pose a problem to
observers.

Evening observers can look forward to activity from the antiapex radiant
and the antihelion Virginids. These two radiants are situated along the
ecliptic some 90 degrees and 180 degrees east of the sun. The exact 
position of the antiapex radiant on Saturday evening will be at 6:45 +23
which lies in central Gemini. This area of the sky lies high in the
northwest at dusk and will set between midnight and 1am. The entire
constellation of Gemini can be considered as the source (radiant) for
any antiapex activity as the the radiant is a large area rather than a
small point in the sky. Any activity from this source would be very
slow, often lasting several seconds before being extinguished. Rates are
usually very low but this may be one of the sources for the famous
"April Fireballs". This is the best time of the year to view activity
from this area as it is high in the sky.

The radiant for the anthelion (opposite the sun) Virginids is located at
13:12 -06 on Saturday evening. This position is in central Virgo very
close to the bright star Spica. This area of the sky rises near dusk and
best seen high in the southern skies near midnight. Like the antiapex
radiant, the radiant area is large (rather than a small point) so the
entire central area of Virgo may be considered a source for these
meteors. The Virginid meteors appear slow near the radiant and up to
medium speed high in the sky away from Virgo. The Virginids also produce
low rates in the 1-2 per hour range. This has also been noted as a
source for fireballs this time of year.

The last "cardinal point" along the ecliptic to produce activity in the
night sky is the apex. It is located 90 degrees west of the sun. Most of
the activity seen from this area is swift and produces persistent
trains. This is caused by particles in retrograde motion colliding
head-on with the Earth.  Any particles moving in direct motion (the same
direction as the Earth) would appear as slow meteors. These slow meteors
from the apex are quite rare. The apex source rises near midnight as is
best placed in the sky just before dawn when it approaches the meridian
(due south). The exact position of the apex radiant on Saturday morning
will be 18:45 -23 which is in central Sagittarius.  Due to the extreme
southern declination this would be the worse time to view activity from
the apex as it lies low in the southeast, especially from high northern
latitudes. Due to this situation rates would probably be very low, less
than one meteor per hour on average. 

Only one radiant remains actives in the far south. The Delta Pavonids
are best seen just before morning twilight from tropical and Southern
Hemisphere sites. On Saturday morning the radiant will be located near 
20:51 -64. Radiant drift for the Delta Pavonids is 6.4 minutes eastward
and 0.2 southward per day. Any shower members would be swift with an
entry velocity of 60 kilometers per second.

Finally sporadic rates are still running higher than normal for
observers watching in areas free of light pollution. This week I would
expect evening watchers to see 5-6 sporadic meteors per hour while the
morning skies should produce 8-10 meteors per hour.

Clear Skies!
Robert Lunsford
AMS Visual Coordinator
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