(meteorobs) Meteor Activity Outlook for May 21-27, 2004

Thu May 20 15:01:50 EDT 2004

Dear meteorobs.org:
       The attached post to this website said that the moon reaches its "new 
phase" on 5/27.  That sentence should actually have said that the moon will 
reach its first quarter phase (Greenwich Mean Time) on that date.
Eric Bynum, Independence, MO
Bynum_9 at hotmail.com
meteorobs.org subscriber

>From: "Robert Lunsford" <lunro.imo.usa at cox.net>
>Reply-To: Global Meteor Observing Forum <meteorobs at meteorobs.org>
>To: "Meteorobs" < meteorobs at meteorobs.org>
>Subject: (meteorobs) Meteor Activity Outlook for May 21-27, 2004
>Date: Thu, 20 May 2004 09:27:43 -0700
>
>  The moon reaches its new phase on Thursday May 27. At this time the moon
>lies ninety degrees east of the sun and will set near 0100 local daylight
>time. This weekend the moon will be a waxing crescent and will set shortly
>after the end of evening twilight. It will set long before any 
>post-midnight
>meteor observing sessions. The estimated total hourly rates for evening
>observers this week should be near two for those in the Northern Hemisphere
>and three for those south of the equator. For morning observers the
>estimated total hourly rates should be near eight for those located in the
>Northern Hemisphere and twelve for those in the Southern Hemisphere. These
>rates assume that you are watching from rural areas away from all sources 
>of
>light pollution. The actual rates will also depend on factors such as
>personal light and motion perception, local weather conditions, alertness
>and experience in watching meteor activity.
>
>The radiant positions listed below are exact for Saturday night/Sunday
>morning May 22/23. The radiants do not change greatly day to day so the
>given 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 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 positions below are listed in a west to
>east manner in order of right ascension (celestial longitude). The 
>positions
>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 Antihelion radiant is now centered at 17:04 (256) -23. This area of the
>sky is located in southern Ophiuchus, five degrees northwest of the third
>magnitude star Theta Ophiuchi. Since this radiant is large and diffuse, any
>slow to medium speed meteor from southern Ophiuchus, northwestern
>Sagittarius, southwestern Serpens Cauda or northern Scorpius could be a
>candidate for this shower. The center of this area is best placed near 0100
>local standard time when it lies on the meridian and is highest in the sky.
>At this time expect to see two shower members per hour north of the equator
>and three per hour for those situated south of the equator.
>
>Unlike most of the annual showers the antihelion source is produced by
>debris from unknown objects orbiting in a direct motion like the earth.
>These objects are most likely asteroids, which produce stony and metallic
>debris whose density is much greater than material produced by comets. This
>material 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 source is active all year from an area of the sky nearly
>opposite that of the sun. The center of this source will move approximately
>one degree eastward per day and travels through many different
>constellations over the course of a year. It may make sense to list these
>meteors as antihelions or "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 send their data to the International Meteor 
>Organization
>should call these meteors Sagittarids (SAG).  The antihelion radiant was
>once known as the Alpha Scorpiids this time of year.
>
>The Beta Corona Australids (CAU) are listed among the radiants of the Dutch
>Meteor Society. The current radiant position is located at 19:36 (294) -39.
>This area of the sky is located in southeastern Sagittarius, five degrees
>southwest of the fourth magnitude star Theta Sagittarii. The best time to
>view this activity is near 0400 local daylight time, when the radiant lies
>highest in a dark sky. ZHR's at maximum activity (May 15) were predicted to
>be only three shower members per hour so current rates would be less than
>one per hour. Observers in the Southern Hemisphere have an advantage with
>the radiant rising much higher in their sky. With an entry velocity of 45
>kilometers per second, a majority of these meteors will appear to move at
>moderate speeds.
>
>The Northern Apex radiant is now centered at 22:04 (331) +04. This position
>lies in southwestern Pegasus near the faint star Nu Pegasi. This area of 
>the
>sky is best placed for viewing during the last dark hour before dawn when 
>it
>lies highest in the sky. Since this radiant is large and diffuse, any 
>meteor
>from northern Aquarius, southern Delphinus, Equuleus or southwestern 
>Pegasus
>could be a candidate from this source. Rates would be now close to two per
>hour regardless of your location.
>
>Like the antihelion area, both apex areas 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. This is
>not really a "shower" per se, but an artificial radiant created by the
>Earth's motion through space. Meteors from both branches are normally
>included in the sporadic count. I feel it is a worthy project to see if it
>is possible to distinguish these meteors from the normal sporadic
>background. On rare occasions there are meteors with a zero inclination 
>that
>radiate precisely from the apex point on the ecliptic, exactly 90 degrees
>west of the sun. In simplistic terms, these meteors are seldom seen since
>the Earth "sweeps clean" much of the material that shares the same orbit as
>our planet. Much more material 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.
>
>The Southern Apex source lies exactly 30 degrees south of its northern
>counterpart at 22:04 (331) -26. This position lies in northern Pisces
>Austrinus, ten degrees northwest of the first magnitude star Fomalhaut
>(Alpha Piscis Austrini. Like the northern apex, these meteors are best seen
>toward dawn when the radiant lies highest above the horizon in a dark sky.
>Since this radiant is also large and diffuse, any meteor from southern
>Aquarius, southeastern Capricornus, or Pisces Austrinus could be a 
>candidate
>from this source. Rates would now be one per hour in the Northern 
>Hemisphere
>and three per hour in the Southern Hemisphere.
>
>The Eta Aquarids (ETA) are produced by particles from Halley's Comet, which
>last passed through the inner solar system in 1986. Even though this is now
>eighteen years ago, material is still encountered every year in late April
>and throughout most of May. We passed closest to Halley's orbit on May 5.
>Current rates would be less than one per hour from a radiant located at
>23:28 (352) +06. This area of the sky is located in western Pisces, one
>degree south of the faint magnitude star Theta Piscium. The best time to
>view this activity is just before the start of morning twilight, when the
>radiant lies highest in a dark sky. With an entry velocity of 66 kilometers
>per second, a majority of these meteors will appear to move swiftly.
>
>The Sporadic rates for the Northern Hemisphere are declining. One would
>currently expect to see perhaps four random meteors per hour during the 
>last
>hours before dawn from rural observing sites. This estimate and the morning
>estimate for the Southern Hemisphere do not include the apex meteors listed
>above. During the evening hours perhaps two random meteors can be seen per
>hour from the Northern Hemisphere. Rates seen from the Southern Hemisphere
>are now stronger than those seen in the northern skies with perhaps six
>random meteors being seen per hour during the early morning hours and three
>per hour during the evening.
>
>Clear Skies!
>Robert Lunsford
>AMS Operations Manager
>
>_______________________________________________
>Mailing list meteorobs
>meteorobs at meteorobs.org
>http://lists.meteorobs.org/mailman/listinfo/meteorobs

_________________________________________________________________
Get 200+ ad-free, high-fidelity stations and LIVE Major League Baseball 
Gameday Audio! http://radio.msn.click-url.com/go/onm00200491ave/direct/01/