The positions listed below are exact for Saturday night/Sunday morning October 26/27. 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 03:16 (049) +18. This area of the sky is located in eastern Aries, 10 degrees southwest of the famous naked eye Pleiades open star cluster. Any slow to medium speed meteor from eastern Aries or western Taurus could be a candidate for this shower. The radiant is best placed near 0100 local standard time when it lies on the meridian and is highest in the sky. We are now starting to see an increase in the antihelion activity as the Earth encounters debris from comet 1P Encke in addition to the normal material. At this time expect to see 3 shower members per hour from areas north of the equator and 2 per hour for locations south of the equator.
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 Taurids or "STA or NTA's" depending on whether the meteors radiant from north or south of the ecliptic.
The Orionids reached maximum activity on the 21st. Current activity would be low due the presence of moonlight in the morning sky. The radiant is located at 06:36 (099) +16, which is very close to the 2nd magnitude star Alhena (Gamma Geminorum). The radiant is best placed near 4am local standard time, when it lies highest in the sky. These meteors are seen equally well from both hemispheres. At 66km/sec., the average Orionid is swift.
The Epsilon Geminids are nearly over. Current rates are less than 1 per hour due to interfering moonlight. The radiant is located at 07:24 (111) +27 . This position is located in eastern Gemini 3 degrees southwest of the 1st magnitude star Pollux (Beta Geminorum). The radiant is best placed just before the start of morning twilight, when it lies highest in the sky. At 71km/sec., the average Epsilon Geminid would be swift, much like the Leonids of November.
The Northern Apex radiant is now located at 08:16 (124) +34. This position lies in southeastern Lynx approximately 8 degrees northeast of the 2nd magnitude star Castor (Alpha Geminorum). 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 eastern Gemini, southern Lynx or northern Cancer could be a good candidate for this shower. This source should provide at least 2 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 08:16 (124) +06. This position lies in extreme northwestern
Hydra, 3 degrees south of the 4th magnitude star Beta Cancri. 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 western Hydra, southern
Cancer or eastern Canis Minor could a candidate from this source. Rates would
be now close to 1 per hour regardless of your location.
The Sporadic rates for the Northern
Hemisphere have now reached their plateau of top activity, which occurs during
the entire last quarter of the year. One would currently expect to see perhaps
5 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 at their annual low with
perhaps 3 random meteors being seen per hour during the early morning hours
and 2 per hour during the evening.
Clear Skies!
Robert Lunsford