The positions listed below are exact for Saturday night/Sunday morning August 31/September 1. The positions do not change greatly day to day so these positions may be used during this entire period. Most star atlases (available at science stores and libraries) 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 which constellations are in 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 location. Meteor activity is not seen from radiants that are located below the horizon. The radiants below are listed in a west to east manner in order of right ascension (celestial longitude). The radiants listed first are located further west therefore are accessible earlier in the night. This list also provides the order of ascending velocity for each radiant with those listed first usually being much slower than those last on the list. Velocity should not be the prime factor for shower association as all showers can produce slow meteors. Slow meteors can be produced from normally swift showers, such as the Leonids, when meteors appear near the radiant or close to the horizon. The true velocity is only revealed in shower members seen far from the radiant and high in the sky.
The Antihelion radiant is now located at 23:32 (353) -03. This area of the sky is located in western Pisces some 5 degrees south of the group of faint stars known as the "circlet". Any slow to medium speed meteor from western Pisces or eastern Aquarius could be a candidate for this shower. The radiant 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 2 shower members per hour regardless of your location.
Unlike most of the annual showers the antihelion radiant is produced by debris from unknown sources orbiting in a direct motion like the earth. These sources are most likely asteroids, which produce stony and metallic debris whose density is much greater than material produced by comets. This debris 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 radiant is active all year from an area of the sky nearly opposite that of the sun. The radiant will travel approximately one degree eastward per day and travels through many different constellations over the course of a year. It is easiest to simply list these meteors as " 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. IMO observers may wish to list these meteors as Piscids or "SPI".
The Gamma Doradids are an obscure minor
shower listed among the radiants of the Dutch Meteor Society. The peak activity
is listed as August 30 with a ZHR of 5. The current radiant position lies
at 04:08 (062) -50, which places it in
eastern Horologium some 2 degrees northwest of the 3rd magnitude star Gamma
Dorado. Due to the extreme southern declination, this shower is only visible
from the northern tropics southward. The radiant is best placed just before
the start of morning twilight. At 41km/sec., these meteors are of average
velocity. Rates are dwindling so this week will offer your only chance to
try to spot some of this activity in 2002.
The Northern Apex radiant is now located at 04:32 (068) +37. This position lies in southeastern Perseus midway between the bright stars Epsilon Persei and Iota Aurigae. This area of the sky is best placed for viewing during the last dark hour before dawn. Since this radiant is diffuse any meteors from southeastern Perseus or western Auriga could be a good candidate for this shower. This source should provide at least 3 meteors per hour for those in the Northern Hemisphere and less than 1 per hour for those in the Southern Hemisphere.
Like the antihelion radiant both apex radiants are active all year long and travel approximately one degree eastward per day. Unlike the antihelion debris these particles orbit the sun in a retrograde motion opposite that of the earth and are most likely produced by unknown comets. They strike the earth after their closest approach to the sun. Since they are moving in opposite directions these particles strike the earth at tremendous velocities often creating bright meteors with persistent trains. These particles strike the earth on the morning side of earth and are best seen just before morning twilight while the sky is still perfectly dark. There are meteors with a zero inclination that radiate precisely from the apex point on the ecliptic, exactly 90 degrees west of the sun. These meteors are rare though as the earth orbits the sun it "sweeps clean" much of the material that shares the same orbit. Much more debris is located just north and south of the earth's orbit with slightly higher or lower inclinations. This creates the northern and southern branches of the apex activity. Meteors from both branches are normally included in the sporadic count but should also be noted in some manner as to which branch of the apex complex they appear to radiate.
The Southern Apex source lies exactly 30 degrees south of its northern counterpart at 04:32 (068) +07. This position lies in southeastern Taurus, 10 degrees south of the brilliant orange star Aldebaran (Alpha Tauri). Like the northern apex, these meteors are best seen toward dawn when the radiant lies highest above the horizon in a dark sky. Any meteor from southeastern Taurus or western Orion could be a candidate from this source. Rates would be now close to 2 per hour regardless of your location.
The Alpha Aurigids peak on the morning
of September 1 with an average ZHR of 9. The actual rates fluctuate greatly
from one year to the next. The last quarter moon will obscure the fainter
shower members this week so rates are expected to be on the low side this
year. The radiant is located at 04:08
(084) +42, which places it in central Auriga some 5 degrees southwest of
the 2nd magnitude star Menkalinan (Beta Aurigae)
. Due to the extreme northern declination, this shower is only visible from
the southern tropics northward. The radiant is best placed just before the
start of morning twilight, when it lies highest in the sky. At 66km/sec.,
the average Alpha Aurigid is swift.
Clear Skies!
Robert Lunsford
AMS Visual Program Coordinator