The positions listed below are e xact for Saturday night/Sunday morning April 20/21. The positions do not change greatly day to day so these positions may be used during this entire period. Most star atlas's (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 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 while those listed last rise later 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 Pi Puppids reach maximum activity on April 23 from a radiant located at 07:20 (110) -45. This area of the sky is located in western Puppis 3 degrees southwest of the 3rd magnitude star Sigma Puppis. These meteors are produced by debris from comet Grigg-Skjellerup which reaches perihelion this year. Activity is normally only produced when the comet is near perihelion so this display definitely bears attention this year. Any activity from this shower is only visible in the early evening sky. Unfortunately the waxing gibbous moon will be in the sky at the same time limiting any possible activity. With a declination of -45, the further south you are located, the better chance you have of seeing activity. As with all early evening meteors, any activity associated with the Pi Puppids would be extremely slow moving compared to activity seen later in the night such as the Lyrids. One must face toward the west or southwest to properly confirm shower association and to keep the bright moon out of your field of view.The Antihelion radiant is now located at 15:00 (225) -16. This area of the sky is located in central Libra 4 degrees southeast of the 3rd magnitude star Zubenelgenubi (Alpha Librae). The radiant lies low in the southeast at dusk and remains above the horizon the remainder of the night. This area of the sky 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 1 meteor per hour from the Northern Hemisphere and perhaps 2 per hour south of the equator. Any slow to medium speed meteor from Libra could be a candidate for this shower.
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 that 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 directly facing the path of these particles. 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. Those who share reports with the I.M.O. should label these meteors as Sagittarius (SAG).
The Lyrids reach maximum activity
on Monday morning April 22 from a radiant located at
18:04 (271) +34. This area of the sky
is located in eastern Hercules 8 degrees southwest
of the brilliant zero magnitude star Vega (Alpha Lyrae). On this morning
the moon will set near 03:00 local daylight time, allowing approximately
2 full hours of unhampered viewing of Lyrid activity before the arrival of
morning twilight. Under these dark conditions expect to see 10-15 Lyrid meteors
per hour in addition to the other meteor activity. Lyrid meteors are usually
medium-swift and often produce trains. Some Lyrid activity may be seen late
in the evening and during the early morning hours, but much more activity
will be seen after moonset while the radiant is located high in the northeastern
sky. Observers south of the equator will see much less activity as the radiant
will not rise very high into their northern sky. In case it is cloudy Monday
morning, limited numbers of Lyrids can still be seen on the nights surrounding
the 22nd.
The Northern Apex radiant is now located at 20:00 (300) -05. This position lies in southeastern Aquila 5 degrees southwest of the 3rd magnitude star Theta Aquilae. 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 southern Aquila or northern Sagittarius could be a good candidate for this shower. This source should provide 1-2 meteors per hour during the last few hours before dawn regardless of your location.
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 has "swept 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 20:00 (300) -35 . This position lies in a remote area of southeastern Sagittarius near the dim naked-eye double star Theta Sagittarii . 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 Sagittarius or Microscopium could be a candidate from this source. Due to the extreme southern declination (celestial latitude) rates would be now close to 3 per hour from the Southern Hemisphere and less 1 per hour from the Northern Hemisphere.
The Eta Aquarids will now begin appearing in low numbers during the last hour before morning twilight. The radiant is currently located at 21:36 (324) -07 which places it in western Aquarius close to the 3rd magnitude star Sadalsuud (Beta Aquarii). This area of the sky does not rise until near 3am local daylight time for most locations so activity is limited to the last hour before dawn. The average Eta Aquarid meteor is swift and often leaves a persistent train. This shower will reach maximum activity in early May with rates that should easily exceed that of the Lyrids for most locations.The Sporadic rates for the Northern Hemisphere are now in decline and will do so until June. One would expect to see perhaps 5 random meteors per hour during the last hours before dawn from rural observing sites. During the evening hours perhaps 1 random meteor can be seen per hour. Rates seen from the Southern Hemisphere would be approximately 6 random meteors being seen per hour during the late morning hours and 1 during the evening hours. Evening rates are reduced due to moonlight.
I will be out of town for the next two weeks
so no outlook will be provided next week. Next week has a full moon so I expect
little meteor activity to be seen. The outlook for May 3-9 will be available
early on May 3.