The positions listed below are exact for Saturday night/Sunday morning September 7/8. 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 Kappa Aquarids are listed among the radiants of the Dutch Meteor Society. At peak activity (September 18) this radiant only produces a ZHR of 3. Being nearly two weeks before the peak, current rates would be very low. The radiant is located in central Aquarius at 21:56 (329) -09. This position is 4 degrees west of the 4th magnitude star Theta Aquarii . The radiant is best placed for viewing near midnight local daylight time, when the radiant lies highest in the sky. At 19km/sec., the average Kappa Aquarid is easily recognized by its very slow velocity.
The Antihelion radiant is now located at 00:00 (000) 00. This area of the sky is located in western Pisces some 5 degrees southeast 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 September Perseids peak on the morning of September 8 with an average ZHR of 6. The radiant is located at 03:48 (057) +47, which places it in central Perseus, only 2 degrees southeast of the 3rd magnitude star Delta Persei . 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 64km/sec., the average September Perseid is swift. This shower is also known as the Epsilon Perseids and the Delta Aurigids. Those who report to the IMO should label these meteors as "DAU".
The Northern Apex radiant is now located at 05:00 (075) +38. This position lies in western Auriga, 4 degrees south of the 4th magnitude star Zeta 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 west-central 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 05:00 (075) +08. This position
lies in western Orion, 5 degrees northwest of the 2nd magnitude star Bellatrix
(Gamma Orionis). 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 Sporadic rates for the Northern Hemisphere
are now slowly increasing toward their plateau of top activity, which occurs
during the last quarter of the year. One would currently expect to see perhaps
12 random meteors per hour during the last hours before dawn from rural observing
sites. This estimate and the morning estimate for the Southern Hemisphere
does not include the apex meteors listed above. During the evening hours
perhaps 4 random meteors can be seen per hour from the Northern Hemisphere.
Rates seen from the Southern Hemisphere are now decreasing with perhaps 8
random meteors being seen per hour during the early morning hours and 2 per
hour during the evening.
Don't forget to help look for a possible new meteor shower reported in the September 2002 issue of Sky & Telescope, tentatively called the "September Taurids ". The peak should be around September 14th from a radiant lying somewhere between the Hyades and Pleiades star clusters in western Taurus. Another possible area of activity this week lies in the region of Aries and Triangulum. Although no significant activity from the Aries-Triangulid meteor shower is expected this year, any observations of this radiant would be of importance. The main radiant appears to occur near Alpha Trianguli, with a secondary radiant located further south near the 2nd magnitude star Hamal (Alpha Arietis). Historically, this shower seems to have a period of 5 or 6 years. The last outbursts were recorded in 1998 and 1999. Other active years, when two or more experienced observers saw activity, occurred in 1934, 1940, 1951 and 1993. So it is possible that enhanced activity may be seen in 2003 or 2004. However, some activity may be seen this year as some activity has been reported every year since 1993. Your data on these showers, even negative results, are important. So we urge everyone to keep an eye out for this activity next week.
Clear Skies!
Robert Lunsford and George Gliba
American Meteor Society